As reddit became more mainstream, people started using gasp emojis. Like, seriously? There are so many gifs and ASCII art you can use to express yourself and you choose the most basic bitch 0 effort reaction?
Imo the gradual acceptance of emojis was one of the few good things about Reddit gaining popularity. Facial expression/body language plays a huge role in in-person communication, emojis allow adding bits of that to text communication.
Personally I prefer an emoji be used to show a joking or sarcastic tone rather than the /s tag. That double take as something sarcastic is heard, absorbed, and then appreciated is the whole point of sarcasm imo. Saying "this is sarcasm" takes away from it in ways that using a tone or emoji that says the same thing doesn't IMO. But that's just me 🤷.
Though there is also the whole, "we don't do x here because we're better than people who do x" attitude that I used to relate to but have less and less patience for as I get older, at least when x is something that isn't hurting anyone.