I think we have to place chess, e-sports or anything similar to those in a different category of sport than table tennis, football etc. But you don't have to exert much physical force to accomplish something in the game.
I am fine with that distinction as long as commentators stop referring to the chess match going on inside the heads of boxers, football players and mma fighters.
Either way, it's more impressive that Harimoto has done what he's done at his age because he's competing with grown men who should have the physiological advantage and the mental advantage.
I don't know that it is obvious that what Harimoto has done is more impressive. True it includes both aspects but the degree to which they are involved is important as well. Certainly the mental aspect of table tennis pales in comparison to chess - so you would have to argue that the physical involvement makes up for it, some how, in some arbitrary equation, of some sort.
I am very impressed with Harimoto and love his take no prisoners never back down approach - but does it stand out as far superior to everything any young athlete has ever done? Not so sure.
In gymnastics it's mainly younger people competing with each other anyway and being younger is where you have the physiological advantage.. if I'm not mistaken.
Two issues with what you say here - first is that the reason young gymnasts only compete against other young gymnasts is because they have already eliminated the older ones at a much lower level of competition. Secondly you cannot have the position that Harimoto is at a physiological disadvantage because of his youth, and claim right after that, the young gymnasts have a physiological advantage because of their youth; at least not with out being a little more specific. Those specifics would limit the meaning to two slightly different concepts in the process. That is all well and good, as long as we are aware that by limiting the focus to certain aspects of the physicality, you are actually diminish the extent to which you are claiming Table Tennis and/or Gymnastics as a physical sport. Much as you did by saying chess and e-sports aren't as completely physical as football.
I am not just knit picking here to be a pain, I am making the point that there are many different aspects to each and every individual sport and they are not so easily compared and so to the accomplishments in each are not easily elevated one above another.