I don't have a problem with snipers themselves, but I have a problem with how they are used sometimes. I often see this happen on Marathon:
a) Team A corners team B with vehicles and kills a building (ref for example, or sometimes strip / WF)
b) HON / Baracks still stands.
c) The team in the defense cannot get vehicles due the strip is lost or the fact they are expansive and IF they can get a vehicle the other team will kill it at delivery, although cause nobody can repair.
d) The enemy doesn't finish it, but instead gets between 2 and 10 snipers and starts killfarming
e) For 20 min till way longer time nothing happens except the losing team buys a unit and gets shot, you respawn, walk out and get shot...
I had rounds of Islands & Field where the half of the team was sniper and some kept going on for 40 till 50 minutes without any progress except some people having a huge K/D.
Now that's when a sniper is annoying...