I prefer to rank/rate college players as if they all die in a plane crash the day after their last college game.
What?
You're not wrong. And I know this is one of your pet peeves, that often people overweight more pedestrian careers of college players because they were NFL stars.
But it's sometimes difficult to rate players because there isn't enough parity in college football. As one of the memes said, sometimes in college football you can see a 1v1 matchup between a future NFL pro bowler and a future... accountant. It can sometimes make players statistically look much better than they are--like you point out with players against G5 competition.
I'll give you an example... Curtis Painter. Statistically, he was a VERY good QB. He bested a number of Brees' records at Purdue, and obviously this was a Big Ten team, so it's not like he was playing against G5/HS teams. Now, as a Purdue fan I can tell you from watching closely that he feasted on the weaker opponents and faded against the better ones; OTOH, Drew showed up against top competition. But as an outsider, you could use Brees' pro success as validation that his college success was evidence of his talent, and that Painter's NFL journeyman backup career as evidence that maybe he shouldn't even be in consideration for a list like this...
That's why I brought up Matt Light's NFL career. Not to say that he should be getting college credit for his time in the NFL, but more as a defense against the question of: "How good or important was he, really? Purdue averaged 8 wins a season during his 3 years as the starter?"
The defense would be that as a Purdue fan, we saw how important he was and hold him in a high regard. He was a key enabler in everything Brees' did. But additional evidence is the fact that he spent 11 years doing it at the highest level, made multiple pro bowls and had an all-pro season, on a team that won three Super Bowls during that time, and was trusted with protecting Brady's blind side. The NFL success doesn't get credited to his college performance, but it's corroborating evidence that he truly was as good as he looked in college.