Also, when writing code it's not unusual (at least among LISP and Haskell programmers) to have the editor replace a word for its corresponding symbol, the most famous example of which is (lambda -> λ) because some people find it easier to parse e.g. in emacs[0]. You can easily imagine doing that for other expressions, like (forall, there-exists, ...etc).

All in all I think it's a matter of preference which is in turn related to each individual's experiences.

[0] https://www.emacswiki.org/emacs/PrettyLambda

Indeed, Slack has native support for ~2k emojis, but not basic math symbols. It's clearly a matter of priorities, not feasibility.