X's and O's are a helluva lot more complex than grammar becase X's and O's are constantly change while grammar doesn't change nearly as often.
It just did.
I kid because I love.
To an extent, I buy your argument. If you study accepted style, however -- not even slang -- you find changes in grammar. For example, faulty parallelism is now accepted in all our mass media. (That's when you say "the car had red paint, blue paint, and went 100 miles per hour." Correct grammar dictates that "had" must apply to all the terms in the series, so you would end up with "The car had red and blue paint, and went 100 miles per hour.")
You don't notice the changes in grammar because by the time they're considered normal, by definition,
you consider them normal.
So prescriptivists say you have to define normal, and stick to it, and descriptivists say that whatever the "new" version is, is correct, once enough people sign on.
And don't even talk to me, no pun intended, about spoken grammar.
As to the Xs and Os being harder, they are, but for a different reason. Your brain is wired from birth to assimilate language, and everybody around you is "coaching you up" from day one.
Your brain is
not wired to play football, and certainly not to understand it at the Xs and Os level. (It
is wired to understand things like tackling, at a basic level, but not in the most effective possible way.)
However, there are far more, and far more complex things going on in everyday grammar than on a football field. The playbook would be dozens of volumes, just to describe your "responsibilities" in everyday communication. Fortunately, the "playbooks" of grammar are greatly reduced by the ubiquitous familiarity each of us has with language.
