Just tax non primary residences at a much higher rate. Housing crisis solved.
In theory this encourages a sort of spreading effect where at some point the Nth property is too expensive to buy to rent or speculate on, which naturally stops the exponential effect of making land lording your full time gig by continuously expanding the portfolio.
However, California even tried to repeal prop13 for non primary residence and it failed! So i'm not sure how popular this idea is.
And businesses can already expense that tax, so it's 20% off, while individuals have been subject to the SALT cap