I see this kind of comment an awful lot, and I have two immediate reactions:

The first is a sort of dumb and dumber "we landed on the moon!" feeling where I actually can't believe that someone didn't know that there used to be a 90% marginal tax rate. Perhaps you live outside of the United States?

The second is that the 90% tax rate is completely misleading, as there were so many deductions and loopholes that hardly anybody ever paid it.

Every time somebody brings up the 90% rate, it's always someone on the left attempting a "We could raise tax rates a whole lot more; just look at how high they used to be". It's one of the most disingenuous arguments in politics.