People are expected to do their own homework, take home exams, term papers, research, or work assignments. Not hand it off to a third party be that third party a paid service or unpaid volunteers.
When a question is asked about a topic that is readily researched then, in my mind, the person asking the question has a responsiblity to do that research.
I have no problem, for the most part, with providing a couple of non-commerical links and references to start the research/find the answer process.
A commerical link could be used, again in my mind, if that link is a balanced tutorial that truly adds technical information and understanding.
Or a basic "yes/no" response.
Both sorts of response were posted above.
That said, if there are remaining questions or issues then that person should state what they believe to be the answers and why. Plus cite applicable resources and references.
And as for "services that deal with writing it" using such services is unethical and cheating. Plagiarism as well.