But of course someone who is set on causing offense can probably manage with any word.
In my observation, that word has the opposite effect of 'finding common ground', so I'm surprised to hear you say that. If finding common ground is what you want to do (which is great), there are other words that should give you even better results.
I don't think that's required. If I call an idea "disingenuous" (or "misleading" for that matter), it doesn't imply that the arguer intended to mislead, but only that the idea lends itself to misinterpretation ("it seems disingenuous to suggest that the protest was violent on the basis of the actions of one or two out of tens of thousands" <- this seems about as polite as anything IMHO). But any way of suggesting that an idea is incorrect or inaccurate risks causing offense--it's a perilous enterprise and no matter which word you use, ultimately you have to lay a lot of groundwork to demonstrate good faith, common ground, etc.
That's my $0.02, anyway.
The etmyology is interesting: ingenuous originally meant noble, which is also only something that would be said about a person (https://www.etymonline.com/search?q=ingenuous).
> The move has no political chance in a Democratic House, but sends a clear, though disingenuous, message about punishing supposed “extremism.”
> He would rather endorse someone with genuine doubts than someone with disingenuous beliefs.
And there are many examples in which "disingenous" refers to things other than people.
> The etmyology is interesting: ingenuous originally meant noble, which is also only something that would be said about a person
I wouldn't be surprised at all if "(dis)ingenuous" originally referred only to people but came to take on a broader meaning. This happens all the time--words are fluid on even very short timespans. Consider the verb form of impact:
> Sense of "strike forcefully against something" first recorded 1916. Figurative sense of "have a forceful effect on" is from 1935.
In only 18 years the word acquired a figurative sense (and I strongly suspect linguistic velocity--the rate of change of language--has much increased in the Internet era--although not uniformly across the lexicon). Considering your Etymonline link dates "disingenuous" to the 1650s, it would be surprising if this figurative sense hadn't developed in the intervening ~370 years.
Anyway, while I do enjoy discussing and learning about language, I have to get back to work. Thanks for the conversation, and enjoy your day! :)
Words are sort of statistical meaning clouds—people have different associations and use them differently. Regional variations play a large role. I'm pretty sure the word disingenuous does imply intent to deceive, though, and it's a significant moderation issue because it's extremely popular in internet arguments: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que....
https://www.washingtonpost.com/sports/2021/02/01/deshaun-wat...
Just like 'shut your lying mouth' is, in fact, calling someone a liar and not merely an observation about some independent attribute of their piehole.
Since internet commenters basically can't ever know that about each other, they're not allowed to direct those words at each other here (https://news.ycombinator.com/newsguidelines.html).