I think a lot of people blame Dean's departure for DayZ's decline.
What decline though? Game is far improved from when he was last there (obviously, 2 years of development will do that), and its hard to say how his presence would have changed it either way. Yea, the player count is lower but thats par for the course with PC games (for the MOST part).
They made a bad choice building the game on Arma 3's engine, and have paid for it since. But the game is in an OK place, and all the competition that people (and I) thought would pass it by have also struggled mightily with the open world survival genre.
Yes, it would have been nice to see him there until 'beta' maybe, but the goal of starting something akin to a business, is basically to sell it for a profit, and thats what he did, and what almost anyone else would have.
DayZ was something special though, my heart never pounded so hard as it did the first time I stalked another person and bludgeoned them with an Ax...and there was that time I got robbed at gun point, hand cuffed, and THEY STOLE BLOOD FROM MY BODY, like out of my veins...while Dayz may never be finished, it really is the tipping point for a large number of games and the new 'battle ground' / 'king of the hill' genre.
He clearly had one good idea, which he never fully followed through on. That's it.
but WHAT an idea, it changed gaming in some ways. DayZ will be listed as an inspiration for a long time by developers. (and a cautionary tale)