Emojis are part of today's written culture because they're so trivially included alongside things being written today. You are fighting a battle that has long ended: they're a feature of communication now. Just like older ASCII emojis, and various other even older nonstandard-standards of comms.
And replying with an exclamation mark, something I've done myself many times, is incredibly ambiguous and not the best example you could come up with here :)
Also, you're kinda talking past each other here in terms of emojis in a message vs emojis as reaction.
What kind of people do you work with?
Edit: Yup, you're a techie. Hint: you live in a bubble.
I also do quite a bit of work in the gaming community which has its own custom emoji culture, a different beast altogether.