Calling 22 lenses "only a handful" is--to put it mildly--disingenuous.
Regardless, so, you're saying that the A9 has limitations. Does that make it any less fast? Your comment is akin to criticizing a sports car that goes 0-60 in 3.5sec for knocks and pings and a rough ride when you don't put premium fuel in it, or more to the point, that a Nikon d500 only provides unlimited continuous shooting when you use an XQD card rather than a SD card.
Maximum performance often requires matching and appropriate inputs/accessories. Looking at the list of 20fps supported lens, I see every Sony lens I have or would want to use for sports/action photography listed including some that I wouldn't use like the 12-24 (why I'd want fast continuous for an ultrawide is beyond me, but it's on the list), and the cheap 50mm 1.8 and 85mm 1.8. The only Sony I have that's not on the list is the 55mm 1.8, no big lost. It appears that only older " economy" lenses are missing like Sony's f/4 16-35 , 24-70, 70-200, and 70-300 lenses. For any photographer likely to want/need 20fps, there are 85, 100,135, 400, and 600 primes, and 16-35, 24-70, 24-105 (comparable in price to other 24-105), 100-400, and 200-600 zooms. You consider this selection problematic? Let me know what Canon offers in RF mount that matches this selection at the same or lower price levels. You can't.
Thus, yes, the A9 is a speed camera. It does have some limitations, but for most circumstances, it's about as fast as it gets. As I mentioned, the only reason I haven't purchased the A9 and am considering the R5 is that I want the resolution that the R5 offers as well as the performance. However, your post is helping to crystalize my thinking. It will be years and years before Canon offers the selection that Sony currently offers, and the prices of RF lenses are mind-boggling. The only "sports" lens I have in EF mount is the 100-400. For me, Canon will need to announce a compelling sports lens (like a 500 or 600mm DO) in RF for me to jump.