You can't find why a particular member was banned other than by asking the banned member. Member's report on why he/she was banned may or may not be accurate. Members are banned for not following the posting guidelines found in the FAQ. The infraction sticky found in suggestions and feedback is a resource that illucidates interpretation of the guidelines.
precisely,Smyrl... if you have been banned in DP, you have to wait on the date when your account will be lifted..
If it's just for racking up infractions, there's no point. Either way, it's bad enough that they are banned. Just leave them be.