It's definitely not always bad CC. I have no CC clothing at all, but whenever I play in Sunset Valley, I get the stuck aging notifications for at least three of the resident teens who all age up on the first night, every single time. But then if I see them the next day, they are all young adults. That's probably thanks to Overwatch. And I do get the stuck aging up for role sims all the time too, though those don't get resolved so quickly.
I once had a teen going steady with the babysitter who had taken care of her youngest two sisters while their mother was at work. She aged up to young adult and he was still a teen, so I decided to have her invite him over and age him up with a birthday cake. This was before I had NRaas mods. When he arrived, he was aged up, but not to young adult. He was now an adult!