Yes. Riot knows EXACTLY what they're doing. The fact is, that despite every single one of CertainlyT's original champions being a balancing nightmare which ruins solo queue and professional play, his champions are fun for the person playing them. They style on opposing champions who don't have nearly as many tools as his champions do.
Getting oneshot a screen away by Zoe? Feels pretty good for thr guy doing it. Playing a champion like Xerath and being unable to do absolutely anything meaningful to Yasuo because he has half a brain and a functioning E key? Makes the Yasuo player feel skilled for dodging all over the place and then dumpstering you for having no tools which work against him. The fact is, CertainlyT's champions sell skins. Kled is two years old without a new skin despite the fact that there are so many potential themes for rider and mount, yet Zoe got a pool party skin already (keep in mind that they didn't want to give Annie one because of the implications.)
Look at the skins CertainlyT's champions have. Darius with two legendary skins. Yasuo with a legendary and a massive fuckton of other skins. Thresh with a legendary and a bunch of other skins. Kalista with a championship skin.
Yes, Riot knows CertainlyT's champions are stupidly unfun to play against, are a balancing nightmare, and are impossible to keep fair in both solo queue and professional play. No, they don't care. It makes them money, and money speaks louder than any board complaints.