But they're annoying to type. I never end up using them because I'd have to go look up the icon for something, then copy and paste. I think phones have keyboard features or something, but I actively avoid typing messages from a phone because it's so slow. This represents another move towards "mobile-first" stuff, which I generally dislike.

You are entitled to your preferences, but let's not dismiss actual practical advantages of emoticon support in Slack-likes compared to IRC. I agree it has costs as well as benefits, but dismissing the real benefit is a bad manner.

In slack, at least, typing a colon begins autocomplete by name, which is mostly how I type them: e.g. `+:+1:‘ to react to the post above me with a thumbs-up.