But the phrase remains a common idiom. And in an internet discussion like this, the rationale that makes it bad form in poker does not apply. I cannot see anyone's reactions until after my action is complete and I hit "reply". And therefore I cannot gain a read and final decision based on my incomplete first stage of the action.
Though the bigger reason for not allowing it, is that it can really add confusion and slow down the game when a person says call and the next person now has to wait until they’re sure the current asshole isn’t going to say ‘and raise’ before they can act.
Oh, and keep in mind that poker is full of assholes who will do all kinds of anti social behavior to gain an edge. So the fact that this is a standard rule really gives some idea as to just how annoying it is to the poker community.
https://upswingpoker.com/angle-shooting-string-bet-raise/