"Don't expend more effort than they are" has actually long been a good principle to have internalized. Someone done only cursory research before asking a question on a mailing list? Give a cursory answer. Someone obviously spent hours trying to figure things out on their own? Give them a good chunk of your time. Someone on HN responding to you with single-sentence responses? Either don't respond, or respond in kind.…
That may be enough in some cases.
Sometimes people are not looking for fully fleshed out high-effort answers. They want a pointer (to documentation, or a repo) to get going from someone more experienced.
Google search may throw up too much information and it is hard to make a choice. A one sentence answer from an expert may be enough to set them on the right path.