[killedbydeath]

There is a large difference in effort needed for being good at spelling and for becoming the best in the world. Not a perfect analogy but you wouldn't call competitive eating a very useful skill just because eating is useful. Also, as a side remark, in most languages I am familiar with competitive spelling would not be a thing. English is rather unique in that it does not enforce spelling or pronunciation rules on foreign words and prefers to take them as is instead.

[OJFord]

It doesn't best in the world though, does it, it determines best in the competition.

I don't really follow your analogy either - surely it's more like knowing how to cook or eat a food, or whether something's edible.

I'd have thought almost any skill is useless at a competitive level.