But if they want a child so badly, it is surely because they want to love them and give them the best they possibly could
Nah, doesn't work like that. There are plenty of instances where people do mad things to have a child, but their reasoning isn't always straightforward. I'm thinking of that couple 10-15 years ago who bought the twins from the US and subsequent reports noticed that they weren't tip-top at caring for them before they were removed by social services.
I don't see a problem with having a baby at 50. 50 is comparatively young these days, most people might be knackered but would be able to cope through the baby, toddler, and primary school years. Secondary school might be alright as well, although by that stage many people would be feeling the reduction in mobility, increase in "niggly" health problems, etc.
So once your child gets to uni, they are likely to be faced with at least one parent who has ongoing health problems and all the limitations that imposes. And if they're an only child, they'll be in the position of a sole carer at a very young age when they should be building a career, having fun and seeing the world, or starting their own family. If they're lucky and have an older sibling (like Tina Malone) to share the load they'll still lack a peer with whom to offload to, who'll truly understand their position.
Coupled with all this is the reduction in pension entitlements and benefits that are gradually encroaching. For someone who's fifty now this might be feasible financially , but by the time my generation is that age I think economics will probably play a part in many people not going down this road.
Having said all that, I don't think "shame on you!" for anyone, male or female, making this choice. I just don't think it's a fabulous idea, all things considered.