This really isn't the wild crazy concept you're trying super hard to make it.
Someone like Wentz is a backup that (you hope) can come in and immediately be mediocre, at least MAYBE give you a chance to compete for a handful of weeks. You give him an entire camp and he knows the offense at a minimum.
If your backup is rookie Jordan Love, he's going to get eaten alive. Or someone like Brett Hundley who you've "developed" but has never actually played a meaningful game.
I didn't say anything about when to draft anybody.
It's simply the difference between having a known or unknown commodity backing up your star. Some teams have veteran backup QBs, usually a guy with a not great ceiling but at least a floor that won't leave you completely uncompetitive. The Packers have almost never gone that route despite being absolutely destroyed by Rodgers being hurt multiple times.
Behind their 25 year old star, they have Malik and Clifford. I'd say they botched that. Why are they "developing" another young guy? Love is 25. This is the exact situation they should have planned for - needing to replace him for a few weeks. If he tears an ACL who cares, they'd be dead anyway.
The situation they are in today isn't a parallel at all to drafting Rodgers/Love to replace an aging star. They have no reason to be doing that. The journeyman vet is the backup they should have. Not this garbage we're about to to suffer through.