There was likely a time when "incel" just meant "involuntarily celibate," without all of the baggage, but then two things happened together.

First, a significant number of "incels," most notably on 4chan, fell into a specific set of essentially misogynistic coping behaviors - primarily blaming the supposed hypocrisy and shallowness of women for their own problems.

And second, a significant number of smugly self-righteous bigots saw an opportunity to hurl self-affirming hatred at an undifferentiated mass of people without suffering the backlash they'd get if it was directed at a group that essentially enjoys protected status, and leaped at the opportunity.

So now the popular conception is that all involuntarily celibate men are "incels," with all that that implies - that they're not just involuntarily celibate, but shallow, hateful, misogynistic losers and assholes.

It could potentially help if involuntarily celibate men who don't share the misogyny of the "incels" had their own label, but honestly I don't think it would make much of a difference in the long run, because there are now enough asshole bigots reveling in their hatred of "incels" that they'd refuse to let anyone get away. Just like all other more traditional bigots, they'd cling to their self-affirming conception that the mere fact that an individual is of a specific ~~race~~ ~~gender~~ ~~sexual orientation~~ relationship status means that they're necessarily foul and loathsome, so their hatred of them is justified.