He's in UXM, Legacy, New Mutants AND WolverTeam, and the only explanation I've seen online that seems to work is that we've hit a point where Frost has been so absolutely neutered, but everyone still wants a snarky obnoxious white-costume-wearing person who talks like they're being written by Ellis, so they're all shoehorning this guy into everything they write.
This kind of character works in small doses, because they end up just dominating any scene they're in, and appearing in so many books is just too damn much.
Also, didn't this guy used to be called "Doctor Death" and fight for Das Nazis in WWII? I have an Invaders miniseries with him doing that in.
He was Dr. Nemesis before he was Dr. Death... IF Dr. Death wasn't just lying about being Dr. Nemesis. His chronology has post-Invaders mini issues written in the Golden Age of him back in the Dr. Nemesis identity, so there's also the explanation that he got his mind back together after Volton shocked him to "death". He was a Nazi fighter before that mini as well, hence my theory that Volton's creator just lied about having been Dr. Nemesis to get the others on-board with his scheme, while the real Dr. Nemesis was busy fighting the Surgeon or something.