I've yet ever to see a rebase workflow fail, and I've been using a rebase workflow since at least 2002.

I do sometimes have to rebase across thousands of commits because I let a branch rot, and that can be hard to rebase, but it can be equally difficult to merge. Instead I use a bisecting rebase approach where I try to rebase straight to the new upstream, and if there's conflicts, abort the rebase and try rebasing to halfway to the new upstream, continuing the process until the rebase was across just one commit, thus I can resolve conflicts directly with the upstream commit that caused them, then restart the process until done.