There was no early leaving in 1983, and teams picked Tony Eason, Todd Blackledge and Ken O'Brien instead of Dan Marino in the first round. Quarterbacks have always had a nasty risk-reward ratio.
And yes, there's Tim Couch. But there's also Troy Aikman, Terry Bradshaw, Peyton, Carson Palmer, and guys who had long if not Hall careers like Bledsoe and Testaverde. All first picks in the draft.
For what it's worth, even back in the 1930s-1950s, when rookies didn't make as much as copy editors, quarterbacks and number one picks in general crapped out at about the same rate they do today. The names Gary Glick, Bobby Garrett, and Bob Fenimore don't ring a bell, and shouldn't, but they were all number one picks, and Garrett was a quarterback, too.
PS: A little trivia. The first college quarterback to be the number one overall pick in the draft AND make the Hall of Fame? That would be Paul Hornung, who of course didn't QB at Green Bay.