What I will say is: I don't think that this is purely a problem that autistic people struggle with, I think that neurotypical people (and neurodiverse people who aren't autistic) fall into the same traps, so it makes more sense to me to attack the specific problem when you see it, rather than to try and identify a cause every time.
I have had limited success in the past walking back arguments and trying to get at the root of what people actually disagree with, and sometimes it works and sometimes it doesn't work, but generally I don't feel like I need to categorize someone to try it. It's often enough to say, "hold on a sec, are you upset with claim X or are you specifically upset about just claim Y?" And if that on its own won't work, then I doubt that saying someone is autistic would make it more likely to succeed.
It is generally good practice to try really hard to stay on topic and to stay very specific when arguing with people. Step back from details occasionally and think about what you're actually claiming, and keep just going back to that. Avoid tangents as much as possible, avoid equating disagreements over details with disagreements over philosophy/broad claims. I will not claim to be good at this: quite the opposite, I struggle with it a lot and I regularly fall into petty arguments with people online that I regret later. But when I am conscious enough to think about it, it tends to make my conversations with people online (outside of rare bad-faith actors) happier and more respectful.
You could also use the more general theory that people think differently to each other to explain this scenario. But such a theory is much less practical in terms of resolving the disputes, whereas the MBTI is excellent at this.
This link isn't ideal, but it's a decent considering it's concise and freely available on the internet https://personalityjunkie.com/functions-ni-ti-fi-si-ne-te-fe...
Saying 'I'm sorry but I don't think we're having the same conversation, ...' and then resetting context might be all it takes. It certainly would be less horrifically offensive haha.
They are about 50% nonsense.
But you could read about Big 5 personality traits, which are not nonsense being pushed for commercial reasons like MBTI.
From what I know of the Big 5, it's not very useful for explaining these kind of miscommunications. You can't explain people misunderstanding each other by saying that one is more agreeable and the other less agreeable, because the Big 5 doesn't say much of anything about why those people have those observed traits.
On the other hand, you can explain people misunderstanding each other using the MBTI by for example saying that one is Fe dominant, while the other is Te dominant, as this model posits distinct underlying cognitive processes which cause the person to literally perceive and interpret the world differently (especially in cases where the stimulus (or language) is ambiguous).
It's possible that there are some “just so” stories with no empirical basis you can build around the woo that is the MBTI dimensions that don't correlate well with validated personality measures and the unvalidated narratives constructed around both the coincidentally useful and totally invalid MBTI dimensions, but that's of equivalent value to “explanations” drawn from astrology or theory of humors.
A large part of the reason why I do what I do is to offset that reaction and let people recognize themselves in descriptions of the Autistic experience.
The strategy you're applying is brilliant and completely sidesteps that defensive reluctance response that seems to stymie so many difficult conversations.
Anyone that's been on HN or Reddit or Twitter or Facebook or any other place on the internet where strangers interact has likely seen a situation where people are arguing about something but clearly talking right past each other. Most of the time when I care to pay attention it's clearly pride or stubbornness or rage blindness that's causing the disconnect. However, there are also times where I can't make sense of it at all, either the person is laser focused on a small detail or tracking their own issue through an unrelated conversation or any other number of confusing interactions that tend to agitate people immensely.
Embarrassingly it just occurred to me last year that there are millions of autistic folks that use the Internet, and it's entirely possible that these disconnects are just an impedance mismatch in how our minds work.
So, after all of that, I think my question is if there is any tactful way to approach the question of whether or not someone on the internet is autistic. I'm pretty sure the answer is 'no' and that we just need to remember that's a possibility and to have some grace online.