"Don't link to other sites or you'll improve their ranking. Link to mine instead" is pretty much what this site is saying.
This is why Google created rel="nofollow"[1] and if you are really worried about where you pass PageRank to it is a much better alternative than linking to some random 3rd party site while passing value back to them.
Since the Panda update everybody should be using rel="nofollow" on all outbound links, otherwise you risk getting knocked back to page 100 should any of the sites you ever link to trip a flag that leads google to classify them as a spammer.
For what it's worth, there are many indications that using more than a few no-follow links on your website 1) hurts your SEO standing, and 2) still passes Link Juice to the external website (just slightly less than its do-follow counterpart).
This happened after Google discovered that people were abusing no-follow - by trying to hoard the website's weight and not sharing it with anybody.
You should definitely not rel="nofollow" all outbound links. Do it to sites that have a risk of becoming a spam site maybe, but a quality site usually doesn't become a spam site overnight and you'll do more harm than good to yourself adding by rel="nofollow" to every single outbound link. Google wants you to link out to quality sites so you don't need to nofollow those.
This is why Google created rel="nofollow"[1] and if you are really worried about where you pass PageRank to it is a much better alternative than linking to some random 3rd party site while passing value back to them.
[1]https://support.google.com/webmasters/answer/96569?hl=en