Do you think the outcome of the Green Bay/Rams game might have been different if AD wasn't injured? By your definition, you're not allowed to think that it might have.
I'm saying that to win the Superbowl takes more than great players. There's many ingredients; and coaches, injuries, and just plain luck are no small part of those ingredients.
Andrew Luck was a terrific young QB, but injuries stole his career and some bad luck on the team in general kept him from the Promised Land.
Peyton Manning had to finally get into the right situation.
I know I won't change your mind (anymore than you'll change mine). It's just our individual worldviews at work. Some of us hope for the best; others fear the worst.
The Rams made the right move if for no other reason than McVay didn't feel he could make Goff any better, and that Goff could not return the Rams to the Superbowl. So they took action.
The alternative is a team like the Niners who KNOW that they can't go far with Garoppolo, but also are spinning their wheels trying to upgrade without too much cost. They apparently were players in the Stafford sweepstakes but weren't willing to go all in. So they're either going to be stuck with Garoppolo or at best a player like Cousins (that the Vikes swear isn't on the market), or a Darnold or a Dalton.
You either go big or go home in the QB sweeps. And you may or may not get what you hope for. But it's better to swing that bat than let it rest on your shoulder.