No this is not the case. Football has all shapes and sizes. You may not be a nose tackle but you may fit at the position of Wide Receiver. Even in Sumo you have all shapes and sizes. No you would not be a heavy weight but that is not all there is in Sumo. Actually Sumo has changed and more fit and muscled types are getting into the sport and winning over the same weight fat guys.Or whether or not one has a successful career in blues, country, pop, rock, jazz, folk, metal, Broadway musicals, soul, or opera. Certain vocal characteristics are very desirable in some of these genres but not so much in others.
The degree of training and the type of training also differs.
Likewise, certain body types tend to lend themselves better to certain physical activities. Mine, for example, is not a desirable body type for sumo, NFL football, or horse racing.
Daniel
TKD in not limited to one size fits all. That is why there are different weight categories.
Even in horse racing. It just happens that that sport has a one size is best. But many sports don't. Plus in horse racing it is the horse, the jockey is just there to guide the thing and weight as less a possible for the horse. If the horse could get around the track and run full out without being whiped the jockey would not be needed.
Again I see this as limited thinking. TKD and most sports have categories that make the sport all inclusive. Even basketball. You don't have to be 7 foot tall to play the sport. Only the centers have to. There are point guards and shooting guards that can be as short as 5'5" Spud, Muggsy, and some others have proven that.
Also the singing analogy has been debunked by Daniel as well. Because if you cannot sing by standards of one genera then there are others. Can sing country then sing pop. Can't sing pop then rap. Can't rap the sing folk. You can still be successful in singing even if you can't sing.
Most singers today can really sing. Studios do wonders with your voice. And when on tour, anyone can sing to a track that over shadows your voice. Smoke and mirrors but it works. Millie Vanillie showed us that.