If anything it's McDermotts and Beane's fault. Too much focus on the defense in league that focuses on offense.
In general I've never minded focusing on the defense. Because that's the one thing Josh Allen can't help you with.
O-line is struggling? You have a QB who can extend plays and still salvage something out of it.
Can't run it? You have a QB who can run it.
WRs suck? You have a QB who can still fire balls into tight windows.
But Allen can't keep the other team from scoring points. He can't sack the other QB, tackle them when they run, cover their receivers, etc. But I think this season is showing Allen needs a little more help than he's got right now. Another receiver would be huge.
(And to be fair, last draft the top 2 picks were both on offense, and one of their bigger free agent acquisitions was McGovern, also for offense...so I do think that Beane/McDermott understand this...)