Wasn't the death of Kupperberg's DP one of the few things to actually come out of "Invasion?"

I think Byrne was able to run roughshod with continuity with a totally new DP because since Morrison's run, the team had been pretty much removed from regular DC (in spirit). Maybe they let Byrne try to bring in a new DP that was more tied into the mainline DC and shed all the Vertigo-esque stuff since that had run its course. (and Arcudi's team was totally irrelevant)