I find the polarization in opinion of Art Tatum's playing interesting, as there is a corollary amongst guitarists. It was either Basie or Ellington who uttered this quote about music: "It's not the notes you play....it's the ones you don't". Some listeners find Art's playing too busy, with not enough notes left unplayed, merely implied. Those listeners prefer a more economical, spare style of piano playing But amongst pianists, Art Tatum is viewed as others have already written here---the Master. That is because players are listening for technical proficiency above all else. It's very difficult to play as Art did, physically. It is for the same reason Buddy Rich is revered amongst drummers, not for his abilities at playing music, particularly.
Jimi Hendrix is to electric guitarists as Art Tatum is to pianists and Buddy Rich is to drummers. I, personally, find Hendrix's playing rather unmusical, with poor phrasing and obnoxious tone (like barbed wire being scraped!). But I am in a very small minority, while it appears Art's playing is disliked by a fair percentage of Audiogon's Jazz aficionados.