When you see them being used "wrong," half the time the poster is just being facetious, and the other half of the time the poster just thinks way too highly of their fave/is delusional.
Iconic definitely
Only the Army should we allowed to use it cause let's be real we're the only ones who know what's iconic and what's not thanks to our iconic and legendary fave
Well anything can be iconic to somebody and everything has some form of impact, so It's more a sense of scale. People view their faves very highly and they project that view onto the world without realizing it.
Both. But it seems like everyone is shifting to 'impact' because they realize iconic is becoming overused. Both are annoying because they're not possible to measure and are both the very definition of a subjective rating.