As a general rule, I agree with this (yes, there a maybe a handful of QBs over history that could elevate the offense past mediocrity).
As far as the Rams (and Goff), it's a similar story. Goff suffered from bad coaching, a bad Oline and mediocre receivers last year. Guess what happened.
Goff now had great coaching, a much improved Oline and much better receivers. Guess what's happening.
Had the Rams not made the coaching change and the critical upgrades on the Oline and receiving corps, Goff would still look awful, IMO.
This scenario has happened many times before as well... as a general rule, QBs succeed when:
* The coaching is good
* The surrounding cast is good
Take those away and the QB success is a crap shoot, at best.