Ya know, lane-exclusive itemization is possible. It just needs one thing to support it.

You can trade champions, why cant you trade lanes? If we got that tiny, small bit of support riot could implement their long-desired lane based meta dictation by forcing certain lanes to purchase certain items.

/sarcasm Just think how much better the game could be if only top lane could buy HP+resistance items, mid laners could only buy AP and lethality items, bot lane could only buy crit and ASP! Supports could only buy eye items, locket, vow, and enchanter items! /end sarcasm