I believe you are confusing two separate issues:
- The purpose of having a Stack Exchange site, and
- What constitutes a good answer written by an expert on the subject.
If copying the work of others is seen as a major source of content for this site, then you're doing it wrong. I'm not talking about the nuances of Fair Use and plagiarism. I'm talking about the end goal of why we have this site in the first place. It's not to answer one person's question however you can get it, but to actually make the subject of "genealogy" better on the internet by creating something of lasting value that helps the thousands of people who come after. If a link and a blurb copied from elsewhere is deemed good enough by those vetting the expertise here, you're not curating good content. If copying stuff from elsewhere is "an essential feature" of how this site is built, then there's little net value in having this site in the first place.
But let me back up a bit —
This site was created to become THE world's foremost authority on genealogy. When a users asks a question (or arrives at this site through search), they should have a reasonable expectation of receiving a well-vetted, expert answer to their question. That's why we are here.
What Stack Exchange is not is a list of links showing people where to find things on the Internet. If you were to seek out the leading expert in genealogy to ask a question, the last thing you want to hear is "read page 147 in Family Tree Magazine." A link may "answer" a user's question, but only in the most superficial sense; it doesn't really add to the substance of the site, nor does it make the Internet better. A link just adds another hop between users and the actual information they are looking for. That's why links are not considered answers on Stack Exchange.
###On Copying Other People's Content There are some true "teachers" on this site, driven by the motivation of sharing what they know and making the world of Genealogy better on the Internet. But we've all had that teacher who just sits in front of the classroom day after day, reading from the textbook from bell to dismissal. If all you have to offer is reading from the works of others, you're going to find this a very unsatisfying experience. Great teachers are driven by the urge to get better at what they do by passing on what they've learned to others, and that's a major motivation behind this site.
But even the greatest teachers and researchers will cite the work of others. If there are great works that go deeper beyond what is called for by the post, sure, cite that work as "further reading." All we ask is that such links be accompanied by original expertise of your own.