Ok so this has taken a turn (one I suspect the op wanted) towards saying a SAH parent has less worth.
I agree @fatdogs that it is a job that requires no qualifications and no need to even speak a language. It doesn't require a parent to even do anything at all if they don't want to. It does however have A LOT of value if it is done correctly. This value I believe is the same as someone who is in paid childcare roles. Let me explain my opinion and reasons for agreeing and disagreeing.
First though I will qualify it by explaining I am a teacher and see hundreds of kids come through schools from all walks of life, I have also been a SAHM and I have also started working part time again twice (most recently and when my DC had just turned one) so I see a lot of perspectives personally and professionally. All in all I took two years off work with a brief spell of four months in the middle part time that didn't work for us.
If you are a SAHP who does nothing except watch tv all day and never interacts with a child except put food in front of it you ARE simply doing a job that a monkey does. Yes you change their nappy and yes you provide milk/food (I'm spanning it across ages because it has differences) but that's your job done! This has very little value and you might as well be back at work and earning. A newborn will let you get away with this because they genuinely have days in the beginning where they eat-sleep-eat-poo-eat-sleep for days at a time and it's exhausting. If you are lazy like me that require boob and literal energy sapping; I expect even worse for bottle fed babies because that requires actual effort and making bottles, cleaning them, warming them and a whole loaf of faff (seriously ladies I take my hat off to you). But that's it. Also that phase doesn't last long in the big picture.
However if you remain this type of parent and you find yourself getting annoyed that a baby is disturbing your daytime to and getting in the way of you going out to see friends then this is the time to get your arse back to work because you're doing the SAHP thing wrong. This is about the time that people shout from the rooftops how hard being a SAHP is and how they have it worse than their working partner. Actually if it's that much hard work you are doing it wrong! It's easy. Sure you have literal shit storms to clean up, you get puked on a lot and the second you tidy something you turn around and it's messy again. But this is just the parenting stuff that you accept because you had a baby. I love it! It's rather like being a teacher actually because you have a general plan of what you want to do that day/lesson but then the mere aspect of introducing a child into the mix means it's more a loose version.
As a SAHP I made my role have value. My DH, who had previously lived alone, no longer HAD to clean the house unless he wanted to (we have a 2yo AND trying to sell the house so occasionally it's all hands on deck). My DH cannot tell you the last time he ironed an item of clothing or washed one. He cooks dinner occasionally and gets the kettle on but the general home jobs are done by me. This he appreciates and adds value to his life because it means when he's not at work he's not cleaning and cooking. Our son has benefitted from me being home because I have taught him to read, to write his name, his colours, his shapes, he has a wide vocabulary and is curious. We have been to music groups, sign language, swimming, football, yoga, art, playgroups, fitness classes and a million trips to the beach, park, woods and playground. He's got constant interaction and is always doing something. Now that he's 2 he needs less concentrated interaction from me and is playing and learning by himself sometimes so I am slowly going back to work and he has the occasional day with friends and family whilst I'm at school. Come new year he will be in pre-school full time and I will be in big school full time. Until the next baby and I will be the same. I have enriched his life and given him a good start. This has a value to him and to us.
However in January when DC does start pre-school that's when the pressures are off me more to be the one who stimulates him from 9-3. My DH and I will probably end up splitting chores more (when he WFH he can get the dinner on let's say) but I expect with the tornado out of the house for six hours a day the daily clean up will be less. In holidays I will once again assume my role as SAHP and SAHT (stay at home teacher). I am very very lucky that I was able to take this time off and I know that. I appreciate the fact I got that extra time with my fast growing baby and I love the beautiful person he has become. Who knows if he'd have been like that anyway but never the less I'm proud of my clever little boy and feel like I have contributed. I am also very very lucky that I have a career that means I get to spend 12-14 weeks a year with him because we are both off school. However I worked hard for that PGCE and the fact I wanted a family one day was one of the driving factors.
I do not think being a SAHP when your children are all in school is as much value as when they are home all day. There are part time jobs that for around school hours, especially when the youngest is old enough for after school activities or you have grandparents around. It still has value. When I briefly returned to work when my son was eight months old it was hard emotionally but even worse it was very difficult financially! We were paying out money for childcare that was only just covered by my wages (I was doing a different job then) and our child was unhappy at nursery. Plus as a bf baby he didn't take to a bottle and was very upset at my going away. Now he's 2 and a half nearly he understands that bf is only at night because mummy goes to school and he survives. (Yes Ive been told it's weird, yes I get hassle for it, but I'll decide when he's old enough).
So I stopped working, I started again, I stopped for a whole year I didn't really need to in theory. I see value to my role as a SAHM but I know that value has a time limit before it simply becomes questionable and a bit slack. If I could stay at home forever and afford to never work... sure I would. But it would be boring! I know when my son starts school in January I'll have a spotless house and nothing to do. I'll be one of those weird mums who stands outside the school fence waving and waiting! At least at work I keep out of trouble. Plus I teach Secondary and the tantrums I see from teenagers are identical to those of a toddler so it's like I never left!
Your wife can work part time, or start a business, she could at least make it so you never need to lift a finger in the spotless house that is organised and gleaming👍🏻😀