All because someone included a smiley emoji while making a donation to a local community foundation. Lessons were learned because of poor planning admittedly but if you don't take emoji support seriously it's probably because you haven't suffered through a critical outage from poorly supporting character encodings.
We aren't a chat company. We don't even write email clients. We process transsctions. And we lost millions because of a single emoji.
For me the parent commenter's phrasing of "first class emoji support" goes rather beyond that, e.g. with friendly emoji pickers, maybe reaction emojis, custom emojis, different skin-tone emojis, etc.
I'd view that bigger level of support as extremely optional for a transaction processing company like yours, though less so for a chat system intended for broad appeal in 2018.
How is it better than just having upvotes and downvotes like what's done on websites like HN, reddit, and Slashdot? Personally, I don't see much value when seeing 5 different reaction emojis right under a comment I post in a Slack channel.
Slack just happens to express reactions using emoji.
I'm sorry. Even in 2018 I cannot take seriously any claim that "support for emoji" is being used to make business case decisions.