Conservative economists used to love to point to the Kennedy cuts, but marginal rates were in the 80-90% range then, that's a very different environment. Everything in economics is relative. Not all comparisons drawn are actually comparable.
Knowing the difference matters. A couple of years ago, lots of smart people were convinced that interest rates going to 5% were going to crash the economy. They were wrong because they were looking at previous times rates had gone up by that percentage like in the 80's when they hit double digits - but that's the wrong comparison. They were ignoring that the 5% increase was starting from zero and investment decisions are not made based on how much interest rates have changed, but on their absolute value, and at 5% lots of potential investments were still profitable enough to keep the economy perking.