To clarify, the site does not currently implement FIDE rules under 5.2.2 at all but I think that very few positions fall under 6.9 where mate is impossible and I agree that an exhaustive check for all positions is infeasible. I would guess that the vast majority of material counts and positions under flag fall have mate possible with help-mates (any series of legal moves), if they don't fall under 5.2.2. That is a gut feeling but probably accurate. and these are already ruled a win by the side with time.
The USCF insufficient material counts, I believe, are the ones where any effort would be feasible to look at, in conjunction with FIDE 6.9 situations. In those, I think I have mentioned most cases (in post 22) and I also think most positions with more material are trivially reducible to one of them (through worst play by the defending side). Again, baring 5.2.2 type positions, which get missed in any method.
Yeah, I understand what is wanted. I agree, that I think that he site's implementation is good enough.
Though, as a thought experiment, I don't think it hurts to discuss what it would actually take and whether or not it would end up being any better.