I've expanded on my objections a bit in a sibling comment, but to address "/s": it doesn't have many of the emoji drawbacks.

It is literal shorthand for a well-defined word whose definition can be found. It is visually distinct, and follows the centuries of typographical design we use to acquire written symbols. And it refers to a well-known concept.

So I have no objection to it.

Of course there are some symbols which are easier to visually acquire, and seem to refer to well-defined concepts. But even the various smileys are unintelligible as to their meaning when taken as a group.

So once one gets off the basic "smiling face/thumbs up/thumbs down" subset I'd say it is a disaster for communication in a professional setting, and is exclusionary in a way that its proponents actually want it to be - as an in-group indicator that makes them feel a part of something that "others" are not.