If an admin was on, you would have gotten a warning. Sadly, non-admins dont do stuff like that, they just kick/ban-polls stright away.
You were only kicked, the reason for that is that a lot of users dont care about the difference between ban or kick as long as its not against emself. When its against emself, they rage. Its kinda.. sad.
Anyway, yes, theres no huge rings. Way too many maps to do that, and you would probably not look at em anyway, so wouldnt those polling you.
As long as you can reach the place by ladder, your allowed to stay there. But if someone removes that ladder, no one else can reach the place. If the enemy cant reach you, its not allowed to stay up there when everyone else on ur team is gone. You cant require the enemy to bring ladders through the whole fight to make up for this.
When you still stay up there when no one else can reach you, your breaking the rules. And then the kick poll to get you down is not random. Tho, the poller are required to state a reason for the kick, and the reason must show that you break the rules.