This is heavily implied in the resume of a motion capture artist working with the series developer Turtle Rock Studios.
Although the consensus seemed to be that Back 4 Blood was never the Left 4 Dead follow-up that many had hoped for, it was still a very entertaining zombie game that probably made developer Turtle Rock Studios very happy.
It reached over ten million players the year after it was released, but last year it was announced that the support was over, and the developers would be focusing on their next project instead.
