Based on article dates it would seem this spam hasn't been around all that long, certainly I hadn't seen it before December. I imagine people would click the link because it's the source of an unexpected spike in perceived traffic. Certainly spammers are testing the waters with this, I suppose we'll soon know how successful it is from the number of copycats and Googles eventual response.
The SEMalt spam has been around since at least June 2014, I got incensed enough to block them from my server and write up how to block them on Apache servers:
This post seems to describe a new technique where spammers never even visit your site in the first place, spamming the Google Analytics servers directly.
Referer spam has been around almost as long as web analytics. What's new is that they found a way to infiltrate Google Analytics, which previously avoided them somehow. I'm surprised Google hasn't come up with a countermeasure yet.
