Just commit, no matter the response. Adding /s is akin to explaining a joke after you tell it. If someone doesn't understand or pick up on the sarcasm, it's not your responsibility to spell it out for them. You add /s because you don't want to be held accountable.
Poe's law is a thing. For the uninitiated: "Without a winking smiley or other blatant display of humor, it is utterly impossible to parody a Creationist in such a way that someone won't mistake for the genuine article."
Tone of voice, conversely, is not a thing over text. This is the normal and intended tell for sarcasm, and without it, we have the problem in point 1. Therefore we have to use /s, winking smileys, etc, to denote sarcasm.
The /s tone indicator on the internet is a relatively recent development. We got by many years without using them.
And how did we do that? With other indicators. /s is just a more specific evolution of ;). But winky face is used for more than just sarcasm, so confusion develops. Thus, we have /s
This is a fundamentally dseems like an argument than in your post, and more or less is just an argument against any sort of progress or innovation. “We got by without ____ for many years, so what benefit could they offer us?”
If communication is intended, then the speaker or writer has a responsibility to make an effort toward being accurately understood. That effort involves using forms, formats, and punctuation that is old and well established, as well as more novel elements of them.