IDK, if it's all subjective (and you know we'll circle back to that in the end), does his reasoning or parameters really matter to you? You opinion won't have to change.
But the criteria he used - and I can't quite agree with - was UX, "User Experience." Now, admittedly, a lot of the folks who had the harshest criticisms of 4e were not complaining about the user experience, having never used nor experienced it, but even so, you can't reasonably discount an established user base from that criteria, it's just not realistic(pi).
If it was just the experience of /new/ users, sure. IMX (and I ran intro games for new players a lot), 4e delivered a much better first-play experience than other editions of D&D (though that's not a stunning accomplishment - D&D isn't the first game for so many players because it's a good introduction, but simply because they'd heard of it). But that's too limited a criteria to be useful, especially in the business sense, because a technically less dysfunctional game is not automatically going to move books, especially not on that strength, alone...
Well, they're in print. Hard to sell books you're not publishing.
And, 5e is riding both a renaissance in tabletop gaming, and an 80s comeback. Really, anything with 'D&D' on the cover would be doing pretty well 'bout now - so long as no faction of the established fanbase was actively campaigning against it (and that's the rub, because it's doubtful any version of D&D /other than/ 5e could have managed that feat, after the edition war, and, unlike the dubious laurels of having technically less effdup mechanics, that actually /is/ an accomplishment).
