The Taliyah problem
If they give taliyah easy access wave clear ie patch 6.18 she would become instantley 100% pick banned no questions asked and super oppressive. There are 2 major issues around Taliyahs champion design and I will touch on both of them. First, her ultimate is super polarizing in pro play, in that 1 good ultimate to a side lane can literally win you the game by itself. Any lead or defeiceit on Taliyah is super magnified by her global pressence, when she gets super ahead she is more oppressive than most, and when she falls behind she falls way harder than most. Her second major design issue is the fact that all of her damage is frontloaded onto her kit AND is in the form of unreliable skill shots. The effects of this are huge, taliyah has a non combat ultimate and passive which means that in order to perform she needs to be able to pack close to as much dmg as a full viktor combo into 3 abilities, which can all be cast at literally the exact same time. Adding on to that, her w into e combo is an incredibly unreliable skill shot sequence, and thus it must have EVEN more damage tied to it since she is only expected to land it about 1 every 3 tries. All in all her kit is so squished up into these 3 abilites that it becomes very polarizing for new players since they are not going to hit the 1 out of 2 spell rotations that the pros are they are going to hit like 1 out of 8, but yet she is balanced to the pro level which ties us right back into the azir and kalista conundrum, when you get good on her she is too good, but because of that she is nerfed into oblivion and is nearly impossible for a new player to succed on. You need to play over 100 games on her before you can feel like you can actually do something at all on her. Riot recently said how you can play yasuo and your first game you will have fun on him and see a healthy path to improvement, this is not the case on Taliyah kalista and azir you need to play over 100 games on them before you really feel in touch with the champion.