Political Memes

Yes because there’s no chance that this would end up having to be paid by every homeowner whose house has gone up in value since they bought it

A chance? Sure. But it would require willful malicious writing of the bill. Many (most?) states have homestead protections for homeowners up to a certain conservative value. That protection could pivot to capital gains trivially. I think it's perfectly reasonable to tax valuation skyrockets in excess of (say) $500,000. The government can depreciate those value skyrockets, and we'd still honestly be paying less than our due since property value skyrockets cause property tax decreases (in most (all) municipalities, property taxes are just the town's expenses divided by property value).

while rich people would just find another loophole to avoid it,

In real state, that "loophole" is a law that exists in most states specifically saying you don't have to pay tax on property gain if you follow a specified process to reinvest into property in the same calendar year. But it's not a loophole if it's the damn law. The only way people are dodging real estate taxes now is because they wrote laws to. A law that says "fuck off, you still have to pay" would absolutely work.

while the government would piss all that extra money away on wasteful spending without addressing any actual problems

Across the world, tax rates are largely proportional to health, happiness, and quality of life of the citizens. I prefer to trust the numbers over someone's distrust of the country they live in.