Adli has been good too, hasn't he? Can you imagine the ridiculousness of spending 100m on the likes of Sarabia, Paredes or Draxler instead of simply using the kids that you already have and are pretty talented. Can you imagine the fact that Kehrer cost more than Edouard, Ikoné and Adli put together and that their transfers happened the same summer?
Yes, unfortunately, I can.
He's definitely had ups and downs though, he's far from consistent, but you can tell the talent is there, we could see it in his few appearances for PSG. I don't give much credence to youth performances at all, but he's shown to be a top youth player then as well if that means anything.
It's as you've said, PSG shoot themselves in the foot when you look at the transactions you highlighted. It's also well known now that PSG produces solid youth players that they can't hold on to and will continue to be a feeding frenzy unless something changes, and I don't see that happening under the current hierarchy.