Jeff Quinn was extreme nepotism. He putzed around behind the scenes for THREE YEARS until he became OL Coach.
Let's stop with the nepotism accusations regarding Rees and maybe put them into some context, because this wasn't hiring Brian Van Gorder.
Rees was a GA at Northwestern, spent a year with the Chargers, was QB coach for three years, then took over as OC during the pandemic following a tenure of Chip Long that fostered tension on multiple levels at The Gug. Not to the point of a player rebellion, but close, and long was a 2018 Broyles Award finalist. Long's personality was way too much like Kelly's and it didn't work despite the statistical successes the offense may have seen on the field. Kelly let long go and made Rees the OC because he's smart, was well liked around The Gug and was someone the kids wanted to play for. He'd also been a part of the staff under Kelly and Long, so it was as much an internal football hire as it was a culture hire.
Rees played for Kelly at ND and was brought in as an assistant coach by Kelly later on. If an alien from space landed on Earth, it would take the alien less than five minutes to understand how the football coaching industry works. It's full of white dudes like Kelly who hire their friends, often to insulate themselves with guys they know and trust because the majority of them are hired to be fired.
Plenty of assistants never work their way up for anything. They get into a P5 job based on someone they know and don't have to spend time coaching at Elon or in the MAC. Everyone's favorite Bro Urban Meyer got an interview with Lou Holtz because Skip set it up without asking Lou first. Meyer never coordinated an offense and became a head coach at Bowling Green. Rees has had some advantages, but I'd say the overwhelming reason he's here is because he's intelligent (despite what all the geniuses here think) and relates to the players.