In all honesty the numbers can seem to work before you have the carefully planned child and it can still all go pear shape.
We couldn't have afforded a second child in Surrey (where we lived and commuted to graduate jobs in London) so we sold our house and moved and now rent, and have 3 kids, and do different jobs.
Staying near family and friends is a luxury many of us do forfeit - I do find the "why should I move away from my family and friends" argument whiny - I grew up "up north" in a picturesque rural area full of houses bought as second homes and holiday lets and to retire to, with very little employment in the area aside from seasonal tourism of course a few public sector jobs, and and also pretty much had to move if I actually wanted a job... Different problem, same outcome
The UK housing situation needs sorting but the solution IMO is to sort the rental market - its stupid that people are so hung up on buying and the private rental market needs a massive regulation overhaul so that renting is a secure long term option, the way it is in many European countries.
People also need to stop looking at the baby boomer generation as the "norm" and realise they are a historical anomaly, a blip, and ignore parents like mine who think their children have failed if they don't own a house, and their daughters have failed if they aren't both smashing the glass ceiling and earning 100k in a management job and raising a gaggle of children while maintaining a respectable happy marriage with an equally career-successful husband.
A bit of re-calibration is needed. In the housing market and people's expectations of themselves and their adult children.