In general, if you hold total dice damage constant, one chance to crit yields the same expected added DPR as two chances to crit on weaker attacks. I see at the link that this build relies on constantly applying reckless attack and holding back sneak attack unless you crit. It's only because you're doing that that having the second attack actually buys you something re: crits. But I guess if you have constant advantage, elven accuracy, and a wide enough crit range that you can expect to crit most turns, then it's probably worth it.
I don't think this build works as written though: Elven Accuracy doesn't work with STR-based attacks, and rage only works with STR-based attacks. It may have been based on an obsolete UA wording of EA.
EDIT: Oh, I see that the thread predates the release of Xanathar's and therefore of the official Elven Accuracy feat. So it definitely is based on the UA version.
The numbers I posted do not rely on holding back sneak attack unless you crit, but I did fail to realize that Elven Accuracy does not apply to Strength-based attacks any more! That pretty much derails the efficacy of the build.