Donno who told you that, but have it straight from the project lead:

> it's fine to link to external sources, but the same basic "content should stand on it's own"-guidelines apply (so no link-only examples and the like)

- http://chat.stackoverflow.com/transcript/117558?m=31845619#3...

Which is pretty standard advice on Stack Overflow; we spend an awful lot of time cleaning up broken links that were probably pretty useful at one time, but...

Disclaimer: I work for Stack Overflow and also really hate broken links.