I answered the question Handling and storage tips for Old Family Bible.
In my answer, I said succinctly what to do, and then I provided a link to an expert site that gives great details on one aspect of how to do it.
I received a comment from Area 51 moderator @RobertCartaino saying it would be better to include those tips here rather than sending them off to another site with a link.
Then over in another qustions, @TAH gave what I thought was an answer, but gave it as a comment. I asked in a comment why not make that an answer instead of a comment, which they then did.
That answer was one with instructions and a link to an external site. I thought it was a very good answer. But then over in chat, @GeneJ asked if this question should be referred to a third party site.
I have not seen anything written up on Stack Exchange that says you should not link to other sites or that answers should not tell people to go to other sites. My experience with Stack Overflow is that a lot of questions are answered this way and they have never been discouraged. My experience with website optimization is that it is good to link to other sites because they notice you and they link back.
Part of the issue may be the question. If it is a list question, e.g. "Where can I get information on ...?", then you'll get 100 answers with 1000 links to other sites. That is obviously bad.
But if a person asks "How do I do ...", and you as a expert know the general procedure and then refer them to the detailed instructions, is that wrong?
I definitely think it is better to refer them to a site with the detailed instructions than attempt to copy the instructions over. That information is copyright and you'll still have to credit that information and a link to that site in that case would be absolutely required. As Robert suggests, I could summarize what the site says in tips, but again (and as all good genealogists do), I'd want to reference my source meaning I'd still need to link to that site.
So I'd like to know what the policy should be with regarding to linking to other sites.