Thornmail off of the Howling Abyss

So my friend and I were just in an ARAM, easily winning our game when suddenly the lowest of the low appeared. I'm talking 3 people who straight up built a thornmail just to laugh at us and causing us to lose. This is not the first time that this has happened to my friend nor I. We believe that the thornmail should not be a purchasable item on the Howling abyss just because it is an overpowered item on that map since there is no good source of life steal or any way to counter-act the item. this item is not allowed on the Twisted treeline, so why should it be allowed on a smaller map, with even more champions? So either riot needs to come up with a way to counter the thornmail (only on the howling abyss) or just dispose of it on said map. I know that people will disagree with this, however I think that with such a powerful item on such a little map should either be nerfed to where it doesnt return damage, is deleted, or has a way to be counter-acted. Thank you for reading this, here, have a cookie.