You're right of course. We should all go out and get a bunch of latex balloons and release them all to the sky, because after all, things are paved, people travel, toothpaste tubes get thrown out, someone will use a single use plastic fork today, and the Pacific has a patch of garbage twice the size of the state of Texas. May as well not make any effort unless we can take care of it all at once. Good plan.
That's an awful lot of vitriol over balloons - I'd say the same about straws, etc. - any one particular issue. No one is suggesting that balloons be released willy nilly and WDW doesn't even sell latex balloons. We should all try to do what we can, absolutely, but pick your battles, right?