My apologies: I misunderstood/misread the optional part of your suggestion. Sorry for wasting your time. :/
So just to reiterate: Your suggestion is for a developer to say “Have a cut of X% of my sales as well as (and this will be the new part) a fee for every ticket support has to answer on my behalf.” If I understood you correctly this time, it sounds like a wonderfully responsible thing to do - but I too feel like this won’t be very popular. But I’m not opposed if that’s what you’re suggesting. (Again: Sorry…)
Still there’s one thing we disagree on and that is the behavior of certain users on itch.io… I do not intend to fight you on it or anything but I feel the urge to share something with you… Within the last week alone I have seen posts and comments I would not have considered possible a mere month ago. Of course I can only estimate the number of such problem cases that support has to deal with, but I think there is a connection between cases like the ones I witnessed (partially hinted at in my previous post) and the recent (drastic) increase in time users have to wait for before their mails to support get answered. (I think it has reached 4 to 5 days now.)
Still: I wish you luck with your suggestion being implemented in some way, shape, or form. But the root issue would still be with certain developers who have no interest in accessibility; as well as certain users who have no interest in getting themselves educated. The developers who would need to opt for taking responsibility the most would still stay unaffected. A newsletter from itch to 100 of their worst offenders might have more effect that a technical approach to the problem - and wouldn’t require updates or bug fixes.