Sure threads go off the rails, that's people being people. It is a forum after all, not a help desk. But often there is good reason to ask clarifying questions. Asking why you want to do something could open alternatives to your issue/question. Explaining why you want to do something in your question also helps to avoid derailment.
And then there are a few trolls on here who live just to respond with some callous or condescending response. Ignore those or block the repeat offenders.