Now your removing item sets?! God, Is riot challenged?

Like memorizing the entire shop is a hard thing? I used to use item sets, made like three of them to my fav. champions. But then I realised that I don't have some items in my list which I badly needed in some of my games. So I went back and added them. But then I thought like what's the point? I can just buy everything normally by browsing the shop and memorizing lists and so on. I didn't need item sets anymore.

They're just not going to implement them in the new client because it's probably too much unnecessary work.

Honestly I've seen custom item sets as a burden because items can get nerfed or buffed so you need to constantly update them.

No, they're not removing them. You'll still have the same item sets you have now.

They're not adding the way to way to maintain/create new sets. You'll have to rely on third party tools manipulating the files on your disk to edit your own sets.