I've noticed that the people who lay into sleep training are almost always the ones that a) had okay sleepers (as in, could get a couple hours sleep at a time reliably, or better), or b) had the sort of set up where they could tolerate broken insufficient sleep for months or years on end. They didn't have the sort of job where they could kill someone if they work exhausted, or have to drive places where they could fall asleep at the wheel, they had family that would come and watch the baby for a couple hours so they could nap in the day, could afford a cleaner to sort the house or didn't have health issues exacerbated by poor sleep. Or their kid wakes up, they snuggle them for 5m and they're back to sleep for another couple hours. It's easy to get up through the night if it's for a short period. Some of us have kids that will be up for stretches of HOURS in the night.
It's easy to slag off sleep training when you have the sort of set up, resources and privilege to be able to cope with poor sleep indefinitely. Not everyone is so lucky! Some people have older kids they have to care for in the day, or health issues that get much worse when exhausted, or jobs that simply cannot be safely done by someone who is delirious with exhaustion. If you've never been that tired, to the point you're nodding off at the wheel or falling asleep standing up, you just won't get it.
I see a lot of negotiating with tiny children over bedtime, the parent almost waiting for permission from the child to go to sleep, or enabling the notion that at 1am if you want to get up and play and have a snack sure, you can. It really is the most loving, kindest thing to teach your kids young that bedtime is sleep time, and the middle of the night isn't time for a snack.
It's so rough for babies and toddlers when they are used to being rocked or fed to sleep, they're put down, then when they wake up 45m later they're suddenly in a different place alone when they nodded off seemingly seconds ago in their parent's arms. No wonder they need soothing back to sleep, perpetuating the cycle. Putting them down, awake, and giving them space to learn to fall asleep unaided so they can do the same when they wake in the night is by far the kindest route. It's not very fair to keep tiny children dependent on someone else to fall asleep. Yes it takes effort and time in the short term but it's worth it. Sets them up for good sleep hygiene and routines for life.
What kid wouldn't want to stay up and play and watch TV and have snacks instead of go to boring sleep lol. We're the adults though and sometimes have to do things we know are best for our children.