I think you completely missed another important point hidden in PG's article, besides the obvious compounding effect, and that is that unrealized gains would be taxed under a wealth tax regime.
To simplify with a ridiculous example: suppose I have $0 to my name and I inherit a family art piece from my grandmother that happens to be valued at $2 million. The next year, under a wealth tax regime of 2% above $1 million, I owe $20,000 to the tax man even though I don't have the money in my account.
That is why I think a wealth tax is a stupid idea. Why not just impose greater capital gains and dividend taxes above a certain threshold, for example? That's where wealth is realized. Until then, you're talking about taxing "imaginary" wealth. (edit: or more generally speaking, taxation should happen on transactions, not on an assumed wealth "state")