4 player co-op games are really popular on PC and releasing first on PC/Steam is better, i don't think the original Vermintide was a huge success on consoles, compared to PC.
When they announced the 2 million copies, 1.4 million were on PC and the rest on PS4/One https://www.pcgamesn.com/warhammer-end-times-vermintide/vermintide-sales-numbers