Skins are special yes...
but idk where I said "sell victorious skins" aka achievement skins..
Achievement skins =/= limited skins
Personally I'd die for a chance to get past victorious skins through other achievements (hell, give me the option to get victorious elise for challenger, I'll never sleep til I get there), but the difference is there is no "achievement" needed for pax or medieval twitch. They simply exist for everybody to get. Difference being.. the methods in which you could get them were (unintentionally) discontinued and there isn't a replacement method.
Championship riven was a limited skin only available through code, and was in fact intended to be limited forever; but here it is as championship riven 2016 in shop.
PAX skins as I stated, would require significant terms to be resold due to PAX itself..
Medieval twitch has literally no excuse for there not being a "medieval twitch 2016" or just resold in general besides "it was a unique system". The skin wasn't limited until the service died, and that was never planned originally.
Its not an unpopular opinion that skins should be special, but there is a big difference between medieval twitch and victorious jarvan.