Get a shield only makes a difference if you know how to use it
Shield is a good counter to Archers, but not to Xbow.
Archers have to sacrifice melee and movement to do ranged damage, which in the end still ends up to be less dmg than xbows.
Xbow can flank and kite you with 9 athletics, and still be proficient and deadly in melee while doing the highest range damage in the game. They can even wear heavy armor and 1 shot snipe you across the map. There are no drawbacks with this OP class.
We all know why Xbowers won't get nerfed because that's all the balancers play. If it wasn't OP people wouldn't be playing it as much as they do now, it's that simple.