[Tom Line]

1. Why they do it.

Search results. Search engines score search results. If you can place multiple links to your site on a well-scored site like Chief Delphi, that raises the score of your own website. That's why a lot of these posts are just dozens of links to the same site. Repeat this thousands or tens of thousands of times and you can boost your site and get the hits you want. Usually to download malware of some sort.

2. Should we report it?

Yes. Every time. Because there is a que of reported items that let mods click through quickly and remove each one. Otherwise they have to guess or stumble across the posts themselves.