Item Sets Oddities

I'm just wondering why a decent number of now-gone items are still in the Item Sets section in League. I suppose they do no harm, but they seem a little out-of-place since they're not actually available in game.

These include: , , , and all of the Bilgewater items. I mean, you could never actually buy the explorer ward, so that makes it even more odd.

I don't mind them being in the Item Sets section. I actually kinda like them there. I was just wondering if there was any particular purpose behind them sticking around in the Item Sets section or if they're kinda just left there. Though that case would be odd since DFG is not available...

So yeah, just wanted to mention these nostalgic icons.