I'm sure you've met situation when your posts deleted because they are off-topic posts. If you don't have any idea about what is off-topic, i have simple explain for you.
Posts which are not related to the subject or what to be discussing are called off-topic posts. And topics are not relevant to hopscotch section are Off-topics. Example, if you ask about Ethereum future in Bitcoin Discussion section, it's a off-topic posts. In some forums members have right to post off-topic posts for trolling purpose but it is not allowed in Bitcointalk so try to avoid it. If you post off-topic posts many times you may be banned.