You can realistically make anything sound as strong or as weak as you wanted to if you just use the right wording.

The hardest part of playing Kayle is finding the best time to ult, the rest is just setting up hotkeys for self-casting W and R.

Yeah, and Yasuo is super easy too. You just find the right targets to dash to. But let me tell you about Taric. His stun may just be a point and click, but it's short range and puts him in a compromising position. He doesn't have the tools to escape, and it's all about careful positioning. Do you think Taric has a higher skill cap than Yasuo? No, that's absurd. Sure, one of the big parts of Kayle is timing your ult. That's a lot harder than you make it sound. I just wanted to illustrate that before going on.

Anyway, if Kayle was so oppressive she would be winning lots of games. You remember post rework Skarner? That is an oppressive champion. His winrate was over 60%. If Kayle had that kind of win rate, I would agree with you. Yet, Kayle's win rate isn't anywhere near that. It's good, and indicative of how she might need a very slight numbers adjustment, but she's not oppressive. And even so, all that means is that she's doing too much damage, and since Kayle isn't like old Poppy where she could be super tanky, super deadly, and go invincible for the entire duration of a team fight, that can be remedied simply by reducing her numbers slightly.

Let me point out the big one to you: Everyone says Kayle is easy. Kayle needs a rework because her kit is so binary and she's so easy to play and requires no thought. At first glance, when you're trying to argue for a nerf on her when you haven't played her, yeah. Then you look at her win rate statistics, and she only has insane win rates in top lane with very experienced players, otherwise they're below average. And for mid, her win rate is well below average for new players. She must not be as easy as everyone says she is. Her kit gives her utility when she's behind, and gives her kill pressure when she's ahead. She has the tools to bully in lane against the right champions, and can split push well. I'd say her kit is perfect, rather than broken. She has plenty of room to be outplayed, just not in ways every other generic gimmicky champion gets outplayed.