I'm going to be that guy and just say that I wince at the use of emoji instead of words. It's not very accessible and I surely hope nobody actually uses emoji word replacements professionally.
On the other hand, emoji are far more international - everyone knows what a thumbsup means ....
In some places, a thumbs up means "Up yours!" Not very friendly at all.
I guess the victory/peace sign would also be a bad example (and that amongst english speakers).
You can call them unprofessional, that's like, your opinion, man, but "not accessible"? Admit it, you made that up because you don't like them and you hoped it'll stick.