I think most people who use it are just scared from the uneducated downvotes/ backlash and I think it just ruins the sarcasm.
I started to avoid using it on other social media as it seems kind of dumb.
My opinion for it on Lemmy is mostly the same but it might work better here if Lemmy had a sarcasm tag instead(the same way NSFW tag work)of /s to signal the sarcasm instead.
I’ve seen at least 4 misunderstandings on lemmy where someone explicitly asked for a /s tag in the end. It’s very much needed.