Is it me or is Mumsnet being played? It seems there are a lot of threads on here just lately all around the theme of defending the status quo and defending Britain's economic and political directions, no matter how much it provably (empirically demonstrable) increases inequality and disadvantages women, no matter how many people it throws under the bus, no matter how many people fall off the system into homelessness.
As you say op, the advantage of buying is that it means at some point you will be able to stop paying rent. You will have an asset, an asset of value in practical terms, that fulfils the basic human requirement of shelter. That can be used for you or for whomsoever you choose.
Those are huge financial and practical advantages to have. In the baby boomer years, more people were able to buy their own houses and were paying them off by the age of 40 - 50, typically. It enabled their retirement. It enabled them to give money to their kids, where that happened. It enabled them to guarantee a roof over their kids' heads - so many people assume that as some kind of automatic right that everybody has, without ever considering where it comes from or realising how very privileged it makes them.
The advantage for the economy as a whole is that the state will not have to support ageing people who can no longer work as well or as long as youngsters. It enables the flow of generations to slip past each other more sociably, without building up the rancour we're beginning to see when certain generations are advantaged beyond others.
It's true there are certain risks to taking on a mortgage, which is the only way of owning for most given that we don't all have family homes or wealth. But the asset stays, and no matter how 'the market' fluctuates in the short term, the value of having an asset that fulfils one of the three basic human needs cannot be understated.
I do not know why people cannot see the value of practical resources any more. Well I do, our entire economy has shifted towards the ultimate make-a-few-people-very-rich scheme, rentier economy: and our entire culture is being loaded with propaganda to facilitate it.