It’s true that the the same teams continue to win their conferences but that doesn’t mean that parity is not creeping in. Parity is not instant. It’s something that evolves. Now, the top teams in the powers conferences don’t have a cake walk to the title. There are teams strong enough to challenge them. As the talent continues increase, the list of teams with a serious shot at cutting down the nets will eventually expand. AZ played in and almost won the NC game last season. Maybe a sign of things to come.
TN had challenges from Vanderbilt, Georgia, and LSU during their reign and consistently lost games every year (one undefeated season), SC has been challenged by MSST (and TN) since.
Stanford almost always had a challenger or two within their conference - recently Washington, Oregon, and OSU have flashed but do they have staying power? Before that UCLA and Cal
Baylor was challenged by OK, TxA&M, and TX at various points
OSU was challenged by various B1G teams over the years
The ACC has rotated a few challengers vs the league leader (It has probably had the biggest rotation of leader and challenger of any of the P5.
And Uconn has been challenged by ND, Rutgers, ND, and Louisville in various years.
I just think that it is too early to say parity is real - there may be more rotation into and out of the elite level of teams but most years still have the usual suspects reaching the FF and the usual suspects winning the NC. The last surprising NC was probably TxA&M ten years ago. Before that maybe Baylor in 2005 or MD in 2006.