As a GM, we detest it when players drop without a word. We know sometimes that an RP doesn’t turn out to be right for someone, but that doesn't make it right to drop without any word. It doesn't have to be a long explanation. In fact, all we'd need really is something like "me dropping. Me no like how RP goes." or "me dropping. Me too little time."

Some GMs might even need to be told their character is terribly overpowered and that that makes the RP unenjoyable. Realizing that might not be something they do on their own. It certainly is that way with many players, so it stands to reason that it is that way with GMs too.