That argument doesn't really make sense. If x were fundamentally simple, why would I need a simple explanation for it? Clearly git is, or can be, complex, and a simple, simpler or simplified explication would be helpful.
None of that implies that "git is [an] unholy clusterfuck of a product," it means that git is complicated. For 99% of the work you do with git, it isn't even that complicated and you don't need to be aware of the data structure. As for the last 1%, well, that's what separates git from other (D)VCSs. Git gives me the power to do a lot, and incidentally, it gives me the power to shoot my foot off too...I still prefer it over say svn or hg, my personal opinion.
It is simple because a simple explanation is possible. Simple doesn't mean "intuitive to proverbial grandmother".
Git is clever, moderately novel and therefore unfamiliar (depending on your background), and simple. There are not many concepts present, and the concepts that are there are not difficult to understand, but those concepts need brief introduction because they are concepts that many will be unfamiliar with.
If you buy a checkers board it will come with a (very simple) rulebook. You aren't born with some sort of natural checkers ability, you have to learn it. Nobody would claim that checkers isn't simple though.
That's not the strongest argument. If you want to get anything done at a reasonable level, checkers is hard (American checkers is easier than international checkers, but neither is really simple).
Git may well be similar: relatively simple rules, yet hard to use proficiently.
Checkers is a very easy game, but with those incredibly simple rules you can get complex behavior. For an even more extreme example, you can look at Go. Git is similar, except there is no competition/competitor there to befuddle you. From the simple components/rules (you've got what, you can perform incredibly complex operations that are infeasible with lesser VCSs.
None of that implies that "git is [an] unholy clusterfuck of a product," it means that git is complicated. For 99% of the work you do with git, it isn't even that complicated and you don't need to be aware of the data structure. As for the last 1%, well, that's what separates git from other (D)VCSs. Git gives me the power to do a lot, and incidentally, it gives me the power to shoot my foot off too...I still prefer it over say svn or hg, my personal opinion.