Because football started in the UK and American football is completely different. Because foot + ball = makes sense... and what the fuck is soccer making sense of? Because American football is called rugby with a little different rules, also a sport from the UK. It's not a big issue at all, at least not for me but that's the logic behind it that makes some people angry.
The real name of what you call "soccer" is "association football," as there are many codes of football: association football, gridiron football, American football, Canadian football, Australian rules football, Gaelic football, rugby football...
The word itself originated in the UK, and it refers to any sport that involves using the feet to kick the ball to score a goal
I suppose because football was invented in the UK and globally football is called football almost everywhere except america. Even in non English speaking countries, It's probably because logically it makes sense to call it "foot" "ball" since you use your feet and a ball.
It used to annoy me but American English of course has differences so it's to be expected. Heck, many words have changed definitions completely over time, a "geek" used to be a reference for a circus act freakshow in it's original context. I expect the differences and don't make a big deal about it.
I guess I'm more irritated when people try to redefine words though but otherwise i'm quite fine with it
When you play the sport with your feet it just seems appropriate to call it foot ball. What if they started calling basketball barrelball it's just stupid, there are no barrels involved in the sport but there are baskets.
Personally I don't really care cause wow it's just words. But uh yea.