Rule 1.9 [backseat administration]

[Spear]

Just because someone breaks a rule doesn't mean you can break another rule to stop them. For an example: you need a vaild reason (a roleplay reason) to cuff someone. Do not cuff someone for an "OOC reason" (Proppushing).
If you see someone break a rule you should get some evidence and post a player report. Otherwise,  just ignore the rulebreaker and/or wait until a staff member takes care of the situation. You could also try to talk to the player and tell him that what he is doing is not allowed. The rule is there for a reason and therefore backseat administration should not be broken. So actually I do not agree with you =/

So if someone spawn a prop and start propbashing cars, you have to "ignore" it? Or whole server must leave because they can't do anything?

That is what we have to do or try to talk to him and tell him that what he is doing is not allowed. Get evidence and post a player report or be patient and wait for a staff member. Even try to call one to the server.
Don't break a rule because others do.