I’m not sure why people are downvoting (without commenting), but I agree.
The main selling point of prop13 was a real problem: rapidly increasing values were driving up taxes so fast that long time residents (of modest means) were being forced out.
I don’t think it’s entirely unreasonable to have some policy that attempts to protect people living in their primary residence from rapid tax increases they can’t afford.
So people were getting so wealthy that they couldn't pay the property tax on their wealth. Yes. The problem is, if you let them decide to tax other people instead of themselves for the spending they themselves approve, they will.
That makes it sound like the increase was due to some inexorable natural force. California's per capita budget is over twice Arizona's, and they're running a huge deficit on top of that. If taxes are too high, cut taxes. If that means you need to cut spending, cut spending. But don't play "hey, let's tax the other guy!" games and expect that to work.
This is a solved problem.
Let people defer increases until their house is sold. This what many states do.
It’s seems insane that we “protect” people whose property taxes are going up because their home is getting so valuable
It really isn't. You could—and we did!—solve that problem by letting people defer property tax payments or borrow against their equity. California literally has a property tax postponment program for seniors. If we just wanted to keep people from being pushed out of their homes by rising house prices, we'd just expand that program.
The point of Prop 13 is to let people have their cake and eat it too: you get to keep the equity you gain from increased housing prices, but not pay the property tax that comes with them.