I think it's a bit more complicated than that. Hard-to-work-with individual have been a problem in open source projects for a long time. What I think is changing is less the personalities of new contributors and more that [sub]projects controlled/significantly influenced by such personalities are getting harder and harder to route around.

It's feasible to fork a project / create an alternative if that's single-digit person-year/year of effort. There's plenty historical examples of that. If however maintaining / creating an alternative would take very significant resources, it's only going to happen if some large corporation foots the bill. Which has its own problems.