Well, let's make the fallacious assumption that they don't. Going from there, an objective analysis of the notes being played (that is to say, what the notes are doing, not simply how many of them there are) showed that although Tatum, like Peterson, had his pet runs and devices used in abundance, many times to excess, he also had at least one or two, maybe even three, higher creative gears that Peterson never did have, especially when it came to harmony. Peterson could take a song and dazzle it into irrelevance. Tatum could take a song and transform it into transcendence. Not that he always did. But he could, and often enough did. Peterson, no. Never.
So, that's why.
The big difference there is that Donald Trump is still alive.