Speaking of them as signifiers isn't useful here, but yes, these are signifiers. You said yourself they convey meaning. The implication of their use wouldn't ha

Speaking of them as signifiers isn't useful here, but yes, these are signifiers. You said yourself they convey meaning. The implication of their use wouldn't happen without signification. One could even write a book about the discourse of affordances. It would be boring and irrelevant, but it wouldn't be wrong. Sorry, just defending the mechanics of meaning.