So .... camping?
Yeah camping... I hear a lot of people complaining about 'camping'.
A person assesses the field and based on tactical considerations and terrain chooses a position to defend. By luck, experience, or a combination of the two, s/he has selected their position well: it is difficult to attack because there is little cover approaching it, or what cover there is does not give a clear shot at our protagonist; it is difficult to hit them with a bang because hard cover protects our protagonist from the only directions a throw is possible; it may also be possible for our protagonist to move unseen from one part of their position to another, so they can pop up and fire from somewhere other than where last seen; crucially the position cannot simply be ignored - the opposition must get rid of our protagonist in order to proceed with their objective.
The only way to defeat such a position is well coordinated team work - several people must provide suppressing fire so that our protagonist has no choice but to make use of their cover, while another one, maybe two, run in to shoot at close quarters... "well coordinated" being the operative term. Suppressing fire doesn't mean a load of shots in the general direction of the enemy, nor does it mean the most common interpretation (in my experience) a few shots at the position and then wait to see if the target pops up. "Well coordinated" doesn't include running out of ammo and needing to change mags while johnny-on-the-spot is relying on that fire, nor does it mean that because one or two people are firing at the position you can leave off an wait to see what happens, or, of those outcomes I've seen with my own eyes, my personal favourite, use the opportunity afforded by the initial attempts at suppressing fire to bugger off and try to advance somewhere else on the field...
Of course most people at a skirmish day do not belong to a team and even those who have arrived with mates have no command structure. Which is fair enough - if we wanted to take orders, many of us would have joined the military. But a curious phenomenon which I've seen play out several times is a group of players huddled in cover as close as they can get forward talking about how they can't get any further because of so-and-so here and so-and-so there, and what can we do? Then someone attempts to put a plan into action requiring the players to act in coordination...
But some of the people who were, minutes before, asking what can they do, who did not themselves have a plan, or voice any objection to the plan put forward by the ad hoc leader, just did not play their part. Later in the safe zone I've overheard such people saying things like "who the fuck does he think he is, telling me what to do?" Now fair enough, I can be a bit abrasive when I'm feeling frustrated, so if it was just plans that I've put forward and seen fail in part or wholly because others did not do their bit, then I could put it down to poor leadership skills on my part (although to be fair to me, this is not true of me in any other area of life and, as i say, whilst i can be abrasive, I am not dismissive or unapproachable), but as a sniper apart from the group i've seen it happen with other people's plans also.
So yeah, being very good at defence irritates attackers who cannot beat you. Hence the petulant yelp, "Camping!"