It should never have taken this long. Brian Schottenheimer might only be 52 years old during the 2025 season, but many other coaches have been made head coaches well before Schotty's current age. Additionally, the former Seattle Seahawks offensive coordinator had significantly more experience than many others.
Seattle wasn't the first place Schottenheimer was an OC in the NFL. It was his third. He also didn't have a bunch of one-and-done positions. He was the offensive coordinator for the New York Jets for six seasons, and the Los Angeles Rams OC for three. No one wanted to give him a head coaching job, however.