I am with you when it comes to coaches not being malleable enough to alter philosophies based on the personnel they actually have. It does raise concerns that Roman tried to convert Kap into pocket passer. Kap has an unbelievable arm and maybe they thought they would give it an honest effort to Manning him but the results were obviously poor. I guess one might side on 'you can't blame them for trying' argument.
In most other cases, coaches are impatient and it seems to follow this internal New HC dialog:
I got three years to win. Is there a sure fire QB on this roster, no or else I wouldn't have just been hired. I need to go out and get my guy, buy time and then win in a couple of years or else I will be gone. Rinse, repeat until a legit QB turns up on your roster.
New coaches, new answers at QB and nary a QB resembling Brady, Rodgers, Luck or Wilson in sight. Bills fans are familiar with program.