Scaling Armor
GW2 does have it already. They are lvl 80 exotic , account bound, crafted sets. There are several.
These sets downscale when you equip them on an alt. Personally I have not tried them out cause, dont need to and I cant sell them since they are account bound so I just havent made any.
I forgot their exact names, but one of them is called ineffable, another protean, there are quite a few. You can just look it up from these 2 keywords on google / wiki.
Heavy Deedz – COSA – SF