Clearly I disagree on that point. It hasn't been (the lack of) D Linemen that kept Texas in the land of suck for ~ 12 years.
For the record, the way you rate QBs as Job 1, I rate QB and OL as coequal Job 1. Without OL, you really never have a successful QB, notwithstanding Colt McCoy's ability to get rid of the ball in .5 seconds. No other QB has ever managed the feat, and none will (and it was still the limiting factor on Colt's teams). It's a stupid idea to even try, IMO, and was born of necessity, not strategy or anything like being optimum football.
No offense intended by my comments. Again for the record, I rank DL just behind OL in importance, so it's not like we have a complete disagreement. We have near-agreement.
(And where you can get by with a semi-cohesive or accomplished D-Line overall, an OL has to be successful as a group; 1 weak link can spoil the entire play of the unit, even when it's a different player each play).