You might be right, in a way,
but you're looking at it one sided...
Peyton Manning was great at being able to be his own offensive coordinator sort of like Tony Romo became the difference though with all those interceptions is like Brett farve you see how many touchdowns they threw.. When you say you averaged about 15 interceptions he averaged almost 32 touchdowns a year entire career he had a couple where he had over 40 in the one year where he had the 55 which set a record.. You didn't realize that scoring especially at that pace can neutralize whatever he might have on the mistakes because he's so confident he can make the plays necessary. What net evident in that battle between Romo and manning the only reason Romo didn't get that win was because he got bumped by throwing on the last drive and it turned into an interception even though it wasn't his fault...
IE the touchdown interception ratio was still great now go look at the touchdown interception ratio of 1 Troy Aikman who played in an offense with a much better run game bigger/better offensive line and typically better defenses and his stat lines are sad in comparison... so I'm going to tell you right now if we're talking about overrated quarterbacks.
I say Troy Aikman's overrated and I know I'm about to get burned but this dude was protected by his offensive coordinator the game plans the run game the offensive line I mean he was on a historically all in type team and he still managed to throw a lot of interceptions...

PM 531 tds 251 Ints Farve 508- 336
Romo 248 -117 wow talk about underrated ; troy 165-141 OVERrated? Dak right now 6th all time td-int ratio 202-74 hmm id say way underrated even by our own fan base..now the best all time and by far unfortunately it's Aaron Rodgers also the biggest tool in the mix but his careers impressive...475-105 but 1 SB? dang just for grins BRees 571-243
I mean this should put it in perspective everyone thought what Drew Brees is safe with the football dude had three straight losing seasons with a great coaching staff a nice roster how does he only have one Super Bowl but dude 243 interceptions I mean maybe you ought to had looked a little further than just Peyton Manning when you compare his counterparts they seem to be very similar...
So when you're looking at a guy who maybe a gunslinger like farve and Peyton Manning you gotta look at their touchdown interception ratio is ridiculous how many touchdowns these guys through compared to their counterparts you get the good and the bad because you got somebody like Daniel Jones who refuses to take any risks and everybody thinks he's safe with the football but he doesn't throw enough touchdowns the man scared to run an offense...
So, I guess it's just about perspective but if you're gonna say someone's overrated then I'm throwing a bomb in here and Troy Aikman is about as overrated as they come he was carried by a great offense... I mean did you look at like Danny white seems to be people say he's underrated he doesn't get enough credit for what he has an upside down touchdown interception ratio that's what I look at how many touchdown did you throw in your touchdown interception ratio not just have a low interception rate and a decent touchdown rate to get you up there on the list but that's why Tony Romo was hated around here because he put a lot of risk but look at how many touchdowns he has as well compared to even our own quarterbacks and I realize they were different eras but if you're willing to Chuck the football and more times than not it's getting you first downs and touchdowns you live with the interceptions...