Here is why your argument is silly.
Comedy is silly.
But comedy serves a purpose in all society more universally than any one sport ever has.
But comedy is by its very definition silly.
Therefore having value does not preclude having silly aspects.
Take this one further:
A troupe of fine actors doing comedy develop teamwork skills and can develop cameraderie and/or rivalry, just like in sports.
Yet what they are doing, if it isn't silly, isn't comedy.
Again, seriousness is not a benchmark of value, nor silliness necessarily a detriment to it.
Mohamed Ali was just one of a long list of sports figures who did not have a problem with making light of anything about his sport. For his legend, that trait has tremendous value.
So-called pro-wrestling is entirely based around how silly it all is, and it makes mucho dinero.
However, I'll meet you half way: sports is as serious as this argument.