cause on one hand, buying property to rent out is one of the ways out of wage slavery

This is not complete thinking. It’s not a way out of wage slavery when you’re just pushing the can down the road and making the condition of someone else’s wage slavery worse. You have to realize that your condition as a worker and a potential tenant’s condition is one and the same, and the way to abolish that condition is to unite as a class to seize and exert political power.

I also don’t really think the answer is all property being state-owned, but what do I know

It really doesn’t have to be. There’s already countries where they have a 95% homeownership rate and that’s been achieved by heavy regulation of housing and real estate speculation, and expropriation programs (also a lot of liquidation of the landlord class).