The US had a tax rate of over 90% for the wealthy in the 1950s (although with loopholes they could push it lower, like now). Didn't seem to have much of an effect on the wealthy, and the US working class did very well.
Reagan, as part of the deal to lower the top rates, traded away those tax shelters.
The thing about tax shelter investing, however, is they only make sense as a tax shelter. They are poorly performing investments otherwise. A tax policy that encourages poor investments is not a good policy.
Keep in mind that the government in the 50s was far, far smaller than it is today. Funding the vast growth in government is inevitably going to get sucked out of the middle class.
And where US gov grew? Army. Where that money goes? To few weapon contractors = to ultra rich. Its not like US put those investments in some other pocket than top 10%
The only thing that matters is what the effective rate was. They could create a 100% tax bracket but if nobody paid it, it's just words in a book.