Casdon "If Gransnet was purely a chat site, with no referencing to other sites for people to find out more about a subject or to verify whether what somebody is saying is true, the membership would dwindle dramatically. A lot of us want to have intelligent and informed conversations about different topics and to do that you need to read more widely." and an intelligent and informed conversation needs input from more than the individuals who are conversing. It also needs reference to comments from others outside the immediate posters, people who have experience of the subject and knowledge of aspects which may not have occurred to the posters.
Readers who don't have the chance to go on a conducted tour like Stardreamer's, with visits to landmarks and places of interest and talks on local customs and crafts, and meals of local produce, can enjoy the virtual tour. So maybe they spend time away from the GN site - but they come back again to look at other threads, and they return next day to see what else is happening. Without the links they wouldn't have found it nearly as interesting.
Do you remember being told at school to "read around the subject"? Didn't you find that more interesting than sticking to a rigid syllabus? Links is a good word for the mental excursions that spice up a conversation. One thing leads to another.