Legitimate strategies, regardless of variety of game or level of play. And although it's generally not my cup of tea, if doing that is how someone has fun in their video game, then so be it.
Spawn camping in old school deathmatches or other games with spawn closets are another story. Believe it or not, straight to jail.
Seriously though, camping a weapon drop or a busy corner and spawn camping are different beasts. Spawn camping sucks because there's not really much if any counter play, it's more on the devs to make spawning less predictable and exploitable. Other types of camping can be played around by being aware of the map.
I usually just get annoyed at game developers for making camping exploitable. It should be used for setting traps, rewarding good strategy, or risky setups that payoff.
I remember this one map in Killzone 3(?), where one spawn was a building with like chutes you could drop out of. Well, the other team could just walk right up to those and actually see into the spawn room so people would camp there throwing grenades and shit into the building. The other spawn was pretty inaccessible unless you spawned there.