Should champions get unique/limited item rosters to buy from?

For example, ADCs to only have access to an item roster of mostly AD items to buy from and only some specific ones (for a rough example can have access to but not etc) instead of having every champion share a single item roster where everyone can mostly buy all of the same items.

Since having all items available to all, item and champion balancing can be difficult since buffs/nerfs overlap which means if you nerf one item you nerf many champions who use it at once, some at reasonable levels and others you cripple and if you buff an item you can inadvertently allow a champion to start using it and become overpowered due to strong synergy of the item's buffs with his kit . If everyone had specific items and limited to them to buy from it could make it easier to make balance tweaks so as to bring champions to a condition which we deem balanced. It could also help prevent 'troll builds' (Jungle Soraka?)

What are your thoughts on this?