If you think your favorite group has been wronged by the company, well first of all you're probably right, think about all the solo artists they've screwed.
JYP - Joo, Baek A Yeon, Baek Yerin and Park Jimin also know as 15& duo
SM - jinho later known as Pentagon's Jinho
The most painful fo me in this list is Lee Hi. Amazing debut album, commercial and critical success, had all the chances to become IU level huge, in fact I'd say was for a brief moment and then nothing for 3 years. Came back in 2016, people thought she's done for but, surprise, another success. At this point anyone with half a brain would think for a second: "damn, we put her on hiatus for 3 years and she still came back strong, maybe we need to do more with her" but nothing for another 3 years. Peak YG dumbassery.