> I don't think the argument that the mere existence of clients that work differently ruin the modern features somehow is really that fair (see below).
It totally does, though. If I write an emoji thumbsup, and the recipient only sees a tofu box, they won't know if I'm agreeing, disagreeing, or saying something else.
If I'm participating in a heterogeneous environment, I need to refrain from including any mission-critical information in a form that can't be read by all of the participants. And since writing the same information twice is usually too much work, the extended functionality winds up completely unused, or at least only gets used for low-value spam.
> Or do you worry that the person you are talking to on slack might just be connected via matterircd via IRC
Yes, I do worry about that. If I find out that one of my coworkers is using a Slack client that doesn't implement all the functionality in the reference client, and can't just talk them out of it, then I'll have to make sure not to use anything that they can't see.
I might even start doing an IRC bridge myself, in fact, since at that point there's really no actual purpose in running a chat client with a bunch of functionality that I cannot use.
A major part of Slack's value is that this is very rare. Almost everyone just uses the reference implementation.