It's an incredibly imprecise statement, to be sure, but there's a validity to the sentiment. In practice, I highly doubt the majority of people find 720p resolution somehow jarring or even noticeable to the eyes, or that it ever crosses their mind that, "Uh, this isn't 1080p, is it?" In the context of arguments on NeoGAF, the whole "being able to tell the difference between 720p and 1080p" thing has become a bit of a meme, but when we discuss that, we tend to do a few things that aren't done in the real world: one, it's a heated argument, where every difference between the systems is highly emphasized; and two, we aren't actually just casually playing the games on whatever system we own and calling one another out for not being able to easily, precisely distinguish between this or that resolution, but specifically putting up side by side comparisons, specifically looking for differences, and constantly getting the differences drilled into our heads.
Now, yes, 1080p is superior. There is no denying that. This is an area where it seems highly likely the PS4 has a very clear, and perhaps permanent, advantage. And anyone should be
capable of seeing the difference between 1080p and 720p. But I don't think it's something the majority of people's eyes are trained to look for. Whether someone buys the PS4 or the X1, they'll easily notice a number of graphical improvements, and they'll probably think the games they're playing look very pretty (especially if CoD isn't among them

). The difference in resolution isn't going to be the deciding factor there - not even close.
So, there's a bit of subjectivity there. Not in terms of actual superiority, because there's a pretty clear cut way of measuring that, but in terms of how much the differences in resolution are emphasized.
Something else that no one should have a difficult time seeing, though: why someone would emphasize frame rates over resolution, or at the very least, why someone would think a version of a game that's 720p but has more stable frame rates is more desirable than a version of a game that's 1080p but apparently has less stable frame rates. Assuming that's actually an accurate description of the X1 and PS4 versions of CoD: Ghosts, I think it's very ironic things turned out that way, considering the nature of the enormous drama surrounding this game.