Unfortunately yeah ahaha. I floated through circles of a lot of the younger artists that @kylebeaudette is talking about when I was getting started (I started out doing Comic and Anime Cons, and that crowd is about 50/50 that crowd and working professionals that do cons on the side like Jake and Will) and have historically made a comment every time Inktober "controversies" pop up along the lines of "whoa wait a second guys, let's stop, actually take a look at everything, and not immediately grab torches and pitchforks" which has never gone over well with that crowd. Kyle's right in that no amount of proof or reasoning will appease them - they've made up their minds.
I've been seeing a lot of those folks cancelling their planned projects this year (a big wave when the trademark thing happened, and a much BIGGER wave now, it's been unavoidable on my feed) and unfortunately to a lot of the people in that portion of the art world, if you're not explicitly with them and hopping on the "cancel" train, you're against them and doing just as much "harm" as they perceive that the "cancelled" person did. It bothers me less now if I get comments giving me flack (I just block and move on), but it breaks my heart to see the community going after one another about this. The art community is supposed to support one another, not tear one another down.
I absolutely agree with @carolinebautista. We absolutely were not meant to decide this, even if we were comparing a book to a book and not a book to a quick flip-through. I think it's horrible that this was brought straight to the court of public opinion instead of being handled through the proper channels, and can already see this having a lasting effect on the art community. The nastier parts of Art Twitter have always been nasty, and I would hope that anyone with a following as large as Alphonso's would know that and not send those people after someone. I've followed both artists for a while and I don't know - nor do I really have any business knowing - if the book was plagiarized or not, it's CERTAINLY soured my opinion of Alphonso. He's certainly taken this and turned it into a no-win situation for everyone.