to hurt mid-major conferences or done out of need to boost resume strength. Its merely a byproduct of the ACC and bigger conferences expanding to be 12, 14, or 15 team conferences.
The power basketball schools could easily schedule up out of conference if they wanted to. Its not like they would need conference help to do that.
I think its a matter of just showcasing their conference more. If a 15 team conference (ACC for basketball) has an 18 team conference schedule, a lot of conference teams will miss out on home games against other conference teams. To go to 20 game schedule gives one more team each season a chance to get a home game against a Duke or a North Carolina.