The primary counter to camping is counter camping, or heavily outplaying the enemy team. The simple fact of the matter is that generally people choose to camp BECAUSE IT PROVIDES AN ADVANTAGE. Therefore, with an advantage that ranges from decent to MASSIVELY BROKEN STAIR OF DEATH, the camping team is logically going to win assuming equal teams unless the other team camps as well. The primary problem I have with camping is that the current "counters" mostly involve being better than the other team. I'm not going to denigrate skill or anything, I love skill and good players, but honestly, if one team HAS to be better than another to fight on EVEN footing, well... That isn't exactly fair, and in a situation like that all you can really hope for is autobalance to fuck up and put all the good guys on the anti-camp team.
This issue is terrible on unbalanced maps where one team has access to an amazing camping spot that they can get to before the enemy team can do anything about. Breakable ladders just make it so that otherwise balanced maps become unbalanced maps as soon as one team decides to camp on a handy unreachable area.
If you'd like, we can brainstorm on ways to beat a team of equal skill that has superior terrain advantage, but I think you'll be forced the conclusion that it requires counter-camping, or outthinking/playing them by a significant margin, because the tables are stacked toward the camping team. Now, it's true that we can always just camp whenever the other team does (And honestly that's what I usually end up doing), but it's boring and tends to lead to draws pretty often due to the flag timer resetting every time someone dies.
Oh, and a random sidenote for all you people who like to bring Reality up as an argument about Game Balance(Yes, I hate you), in "Reality" I could light your shitty house on fire under you, forcing you down. Or smoke you out etc in certain other situations. So, bringing up the fact that you could "realistically" hide on roofs or what have you means nothing, because "realistically" we'd have a shit ton of methods of dealing with it.