Not sure if it is an unintended consequence. You'd need to compare to roster turnover numbers pre-portal. Outside of the top 100ish recruits there used to be a TON of roster turnover in college basketball. I personally know three guys where the story preportal is something like this: go to lower level Pac10 for freshmen year, understand that no matter how awesome you were in high school, it is a different level, finish out at an HBCU or go to good mid-major like Creighton, get buried on depth chart for two years, bounce around to other schools potentially as a walk on and never get traction.
Basketball coaches are ruthless and they generally arent in the business of carrying scholarship players for four years that won't contribute. They typically get counseled out of the program.
There are some notable exceptions including Coach Drew, and Duke under coach K where noncontributors are allowed to keep returning.