It's all dependent on the builders taste, not just about maximum performance squeezed into a certain budget. In the $2000 class was also a full custom loop paired with a 7700k and 1080. That's a great setup for 1440p gaming, without sacrificing just to squeeze in a sli. Would have looked awesome, possibly, when finished but the builder didn't name the build, so the vote didn't register it. I would have voted for that based on originality alone, as I did for the Lian-Li build. Not the best performance, but a killer lookin build that'll do the job nicely.
The 7700k does run hot, especially under full core loads and higher vcore and the big liquid coolers have the one thing no current aircooler can touch, the highest TDP ratings. So AIO's in a max performance setup make a lot of sense, especially on something like a 2011-3 setup where ram channels on the back side seriously compromise aircooler mounting.