This is almost certainly untrue. The issues is that at any asset level, the tax itself can force a sale, which forces realization of gains. Whether that is on-balance more than the value realized is another question, but it definitely could force a sale at any asset level depending entirely on the ratio of your liquid to non-liquid assets.

So, in effect, the question is, should the government use tax as a club to force you to sell assets? Does this have any benefit for the economy/society?