Using reactions in chat apps is popular but I've never seen it have any practical purpose. I think the reason Microsoft added it to Outlook is obvious though, because it's popular in chat apps so somebody at Microsoft decided their old boring thing should have the popular new thing, because that would be good for their career.
In our company we work a lot remotely and everyone is in chat when working hour. Emojis are used a lot. It's much less disturbing if n people give a thumbs up to acknowledge a message instead of everyone typing a new message "OK". Especially when they read hours later.Also "working on it" is common if someone reports a problem.
Additionally emojis serves a social purpose. Instead of chatting in the office kitchen there are all kind of humorous reactions.
Same for us. If I write in the general channel that I will be five minutes late for the meeting, I don’t need everyone to say, „okay, thanks for letting us know“, a simple thumbs up from someone is enough to know at least one person has read this and will inform the rest, if necessary. And that goes for a lot of situations - I’m gonna deploy, looking at this bug now, just ping me if you need help… all of those messages don’t warrant a full reply, just a short token of acknowledgement or appreciation is enough and doesn’t force you to come up with a polite string of words that do the same thing, but more verbose.
