But tone is important, and you know it's important. You said yourself, "no matter how I try to write it out, I feel like I come off sounding like a prick". You're tone policing yourself. And that's a good thing, if it means you're signaling respect for people despite disagreeing with their ideas and/or actions. If it means you're thinking about how to translate your ideas in ways that are more relatable to them instead of insisting that they have to do all the mental work of meeting you where you are. If it means you're treating people like human beings rather than numbskulls who would be beneath your notice if only their stupidity didn't make such a mess of things.
If you get advice from books like Crucial Conversations, if you read literature on psychological safety, if you measure stress responses, and so on, a huge part of that is about tone.
Even if you're fairly neurodivergent, you can with effort learn to do these things decently (c.f. "masking"). ChatGPT, for instance, is an infinitely patient friend in this regard.
Example:
Me, to ChatGPT-4: Can you rephrase this text to be more polite: "But the things I’m posting here? They’re just common decency that anyone with two eyes and an open-mind should be able to see for themselves."
ChatGPT-4: Certainly! The text can be rephrased to sound more inclusive and less assuming: "I believe the concepts I'm sharing reflect basic courtesy and I hope they resonate with people who are open to different perspectives."
A little vague and and perhaps too insipid, but I gave it no context, so it's not a bad effort. If the full spectrum of attempts you make contains only language that makes you sound like a prick, as you put it, help is, now, easily available to you to broaden your choices.
If you were writing cogent logical arguments, then tone policing would be a fallacious reason to dismiss the arguments.
If you were personally afflicted by some grave injustice, then tone policing would be a completely inappropriate justification for overlooking the atrocity.
But if the sole point of writing is to persuade--to persuade!--people to act differently than they otherwise would, tone is going to matter. It's relevant. It's a fundamental skill needed for the task, and other people can and should point out when it's not up to the needed standards so that you can improve.