Here's my point: when websites offer awesome things that seemingly would reduce the amount of traffic they get, the cumulative effect is increasing traffic.
Flickr offers robust APIs. With them, you can upload, download, browse, whatever. You could be a heavy Flickr user and barely ever visit the actual website. As such, it is a huge and successful service. It probably wouldn't be otherwise.
Nearly 40,000 people subscribe to this blog (according to FeedBurner stats) and can read every word of it's content without ever visiting the site. 20,000 people visit the site every day. Would I increase traffic by turning off the RSS feed and making those other 20,000 people visit the site to read? Nope.
When you link to something, link to IT, not to YOU which in turn links to IT. We do this on Script and Style, and I even have the links from S&S which I syndicate on this site go directly to the source. Admittedly, the Twitter S&S account doesn't do this, because we just haven't figured out how yet. "Removing the hoops", as it were, makes you a more credible source.
Take it with you
I put "Add to Coda" and "Add to TextMate" buttons on all the snippets on this site. Now next time you need that snippet, it will be right where you need it, not on my site.
It's about visitors needs, not yours
The reason it works like this is because you are always better off accommodating the visitors needs over your own - even at the short-term cost of "hurting" yourself.