The question is not whether the alternative is perfect, the question is can it be made better than the status quo. It’s not that hard to come up with potential mitigations for the problems you state.

- A taxable threshold, so people who can’t afford lawyers and accountants don’t need to deal with it. Works well for family gifting.

- You don’t need to tax immediately, tax it when it the profit is realized, eg. When you sell that art.

- Taking out a loan against an asset at an increased valuation should trigger a taxable event. (Eg. Stocks go from 1b to 2b valuation and you take out a 500m loan. You are realizing 250k of gains and should pay tax on that gain.)

- Eliminate stepped up cost basis. This is a ridiculous give away.