Before downvoting, check the community.
If you fail to use the /s tag or specifically call out that your comment is sarcastic, I'm going to treat it as being earnest. I might ask if you're being sarcastic, but I will downvote as though you are being earnest.
The /s tag not only clarifies, but it also confirms that you're being sarcastic. A thing you cannot ordinarily convey via written text unless you specifically call it out. You can hint at it, readers can infer it, but you cannot convey it. To convey it, sans directly stating it, you would need to include a recording of you speaking the comment, which defeats the whole point of text chats.
"It definitely reads as sarcasm, you're just missing it" So what? I'm neurodivergent. I barely get this shit in its normal, spoken context. Why should I be expected to understand the implied sarcasm in your text comment?
"Telling someone you're being sarcastic ruins it" Unless your definition of sarcasm is just lying to someone's face, you do indicate sarcasm when speaking. Via the exaggerated, deadpan tone you use. Something you can't convey in written text unless you specifically call it out.
"I made it very clear via hyperbole that it was sarcasm" Have you talked to people? Your obvious, over-the-top, hyperbolic sarcasm could just be someone's opinion taken whole cloth. In fact, you probably modeled your exaggeration AFTER a person. Can you see why, if I don't know you, there's no way to tell?
"I forgot the tag" cool, if I see the edit adding it back in, I'll revert my downvote. Consider it the opportunity cost of forgetting.
"It doesn't hurt anyone" Yes, it does. You give credence to your exaggerated position that you would never take because the people who think like that exaggerated position will point to your comment as proof that they have support. It's why 4chan rebirthed nazism.
"I still won't do it". Then have fun with the downvote. You want to make the internet worse? I'll be sure that you don't get the internet points your brain craves.