There are many, many useless posts in fora these days. A lot of it is dis-information; ranging from deliberately unhelpfull to downright dangerous. And many of those posts are answers to questions.
But, a few of those useless posts are the questions, themselves. These seem to fall into two broad categories:
1) I want to implement this complex, fragile and esoteric solution to a simple problem, but can't figure out how to do it, and
2) I want to implement this common solution to a complex problem, but don't really want to read how to do it, or understand the implications.
Usually, the answers I see to these sorts of questions fall into your two groups of "useless answers". The first answer is usually phrased "You are trying to solve the wrong problem", but I guess you could paraphrase it into "Why would you want to do that in the first place?" This answer is usually given by someone who sees that you are taking the wrong approach to solving your bigger issue, and is trying to guide you to the simpler solution.
The second answer is usually phrased "Please read this handy guide that someone took days to write to assist you with this exact problem" (OK, I lie; it is usually phrased "Why don't you Read the Fine Manual?"), but I guess that you, in your frustration at not receiveing an immediate, detailed-yet-simple-to-follow technical answer to your question might see this as "Why don't you look at X poorly written documentation page " . Of course, your problem is complex, and you haven't given all the relevant facts (some, you don't even know that you need to know), but you'd rather that someone else take the (possibly hours) out of their day to read the documentation, research your issue, locate or invent a solution, write out the solution as a set of tailored-to-your-situation simple-to-follow instructions, and post those instructions immediately in reply to your query.
Buy the way, "You're welcome". But, then again, should I have done all that in answer to your question, you wouldn't have thanked me anyway.