In this context, the discussion is about receiving unnecessary advice, so I think speculating on why this is happening is entirely reasonable.

To illustrate why it's annoying, it may help to provide the most extreme example to date. A couple of months ago I made a post on the open thread about how having esoteric study pursuits can be quite isolating, and how maintaining hobbies and interests that are more accessible to other people can help offset this. I asked for other people's experience with this. Other people's experiences was specifically what I asked for.

Several people read this as "I'm an emotionally-stunted hermit! Please help me!" and proceeded to offer incredibly banal advice on how I, specifically, should try to form connections with other people. When I pointed out that I wasn't looking for advice, one respondent saw fit to tell me that my social retardation was clearly so bad that I didn't realise I needed the advice.

To my mind, asking for advice has a recognisable format in which the asker provides details for the situation they want advice on. If you have to infer those details, the advice you give is probably going to be generic and of limited use. What I find staggering is why so many people skip the process of thinking "well, I can't offer you any good advice unless you give us more deta-...oh, wait, you weren't asking for advice", and just go ahead and offer it up anyway.