I'd say fascists are better at building pipelines because (1) there's a bunch of right-wing money funneling mass numbers of radicalizable people their direction, and (2) fascists make a concerted effort to pull people that last mile from "Republicans are too centrist for my taste" to "Blood and Soil." Years ago I remember seeing effortpost taxonomies of different slices of the right and what specific topics to raise with them that would push them even further right. I think they do purity test a fair amount (wasn't there some Proud Boys kerfuffle over their leader, who turned out to be a fed, not being white?), which is what leads to those pissing contests.

The takeaways for the left are that (1) we also need some connection with mainstream politics that puts us in touch with mass numbers of radicalizable people, and (2) we also have to make a concerted effort to move people from "Democrats are too centrist for my taste" to "workers should own and control the means of production."