Because I sometimes like to argue, I disagree.
1.) A pitcher can use one particular grip on more than one type of pitch.
2.) Hitters usually don't have time to A - see the grip, B - identify the pitch, C - make adjustments before the ball arrives.
3.) Base coaches, while having the best view, don't have time to relay the information to the hitter.
(I once heard a pitching instructor say that they wore long sleeves when pitching because batters could tell what pitch was coming because of which muscles were tensing up on the forearm...
)
So , while I'm sure there are people out there who say I'm wrong, I don't see this as much of an issue.