Why do Dems constantly talk about the 90% tax rate?

So from the years 1944-1963 the government imposed what was supposed to be temporary taxes to recover from the wars however if we actually look back at that time we can see even with such a massive tax rate the government still only collected about 19% of the US GDP. So not only did the GDP take a significant hit after these taxes were implemented because siphoning money from the private sector reduces what's left to invest and grow the economy but obviously the top earners started changing they way their income works leading to what we have now where the top 1% pay almost no income tax but opt for capital gains or to barrow against their assets and pay private interest. Isn't it pretty well known that Elon and other billionaires pay themselves $1 income, would they really feel better taxing Elon for .90¢?