Two reasons, IMO.

1) control over your candidate selection. Much preferable to hire enthusiastic newbies rather than bitter dudes who got held back by the COVID. This was proven over the last couple years when young people skipped over a lot of guys with a salty attitude from the lost decade.

2) To maintain the illusion that there’s a shortage, and keep the right seat of the regionals staffed with these guys, while the current regional list stays firmly planted in the left seat. Permanently.