cRPG shouldn't be balanced, it shouldn't be realistic, it should be FUN. Ladders, and Siege Shields add to the complexity of the game, making it more interesting and FUN. Sure, dirty tricks are dirty, but when you defeat that roofcamping team with even more excellent tactics, the level of satisfaction is equal to nirvana. There's nothing a ladder brings to the game that can't be countered.
I say throwing, for me it's the bestest. You don't get as many kills, but it's so much fun. Especially when people don't expect it. Sometimes it also helps your team, throwing people off, and directing their attention elsewhere. Also, stun.