Snipe is easy to counter. L2P!
Sure, they might get a single kill if you aren't prepared, but they are only a nuisance if you aren't expecting them. They are more annoying in Cyro than BGs imo, since its easy to single them out and counter them out of 8 enemies and less so out of 24+. Not to mention its easy to be on guard for them for a 15 minute match and less so to stay on guard for an hour long open world session.
If you are ranged, like a magsorc or magblade, you should have no problems killing them before they kill you, and if you fail they will still likely run away after you start to damage them.
If you are melee, you have options to counter them while closing the distance:
Stam and magdk can use wings.
Warden can use Shimmering Shield.
A stamnb can roll and enter cloak.
Templar can use Eclipse.
Stamsorc has high movement speed to take advantage of to quickly los and close the distance.
All players can line of sight, or use Sword and Shield ultimate Spell Wall to counter them.
When I see/hear a sniper in a BG match, I know I'm going to easily get a high KDR because they are dumb enough to play the most counterable playstyle in the game.
really good points, particularly on how to counter snipe...
I'd add though that sometimes you can run around around a rock, tree, building - on the other side of the map - and, snipe will still stay locked on to you...
it's like a freaking guided missile at times...