Generally, buying a house is a good long-term strategy.

The essence of it is that this is only true if housing prices continue to go up, which is fundamentally at odds with the societal goal of housing being affordable. Houses cannot be both cheap and good investments. Over the past ~100 years, housing has been treated largely as an investment vehicle, which has created the current mess where you're golden if you're rich enough to buy and thoroughly fucked if you can't.

We've been grossly underbuilding for decades relative to population growth in cities, and this is the result. We'd be much better off if we built enough to make housing a non-issue and left the investments to assets that aren't required to live. But also, depending on the market, rents can be cheaper relative to a mortgage such that investing the difference in stocks etc. will have you pull out ahead. That's beyond the fact that, in some markets, down payments are simply out of reach of most people. I'm in Manhattan, and a decent condo clocks in at around a million. I might get there if I get married and we save for a solid chunk of time, but this isn't a place where a young person can move and quickly decide to buy a place. Renting isn't a bad thing in situations like this.