I can imagine having a debugger or repl open in an emacs buffer, which could be printing out arbitrary strings, which could include emoji. Though non coloured glyphs would be fine in that case.

Also, people use emacs for all kinds of crazy stuff, like IM and email and so on ...

In my day we did all our programming with uppercase letters. Code should be congruent to speech, which does not have letter case. Best practices dictate that identifiers and keywords should never differ only in case. Thus as a programmer I have no need for lower case letters to do my job.

Unfortunately the "normies" won this battle and now I have to deal with the complexity of pressing the Shift key all the time.