This is both true and irrelevant. It is completely possible to avoid blown highlights and noisy shadows with any point and shoot camera. At the size pictures are presented on dating sites, the optics and sensors of any point and shoot are also more than adequate.
More clearly: that the pictures taken with point-and-shoot cameras are crappy is not the fault of those cameras, and pictures taken at the same time by the same person with a different camera would likely also be crappy.
speaking as a crappy photographer, I disagree. A nice camera with a reasonable lens makes up for a lot of photographer incompetence. I mean, yeah, my photographs, in general, turn out much worse than photographs taken by a person who knows what they are doing. However, my photographs taken with cheap point and shoot cameras, well, you can't even tell what the subject is half the time. A good camera brings the picture quality up to "you can read the serial number off the equipment if you zoom in" - I mean, the composition isn't any good, and I've got flash glare, but it's a /huge/ difference.
and, considering that for most things I take photos for (usually something I'm selling) have a relatively low 'good enough' bar, a good camera is the cheapest way for me to get above that bar.
Actually for the same size lens, a larger aperture (lower f-stop number, e.g. f2.8 vs. f8) always results in less depth of field. More precision, better design and better optical quality glass all cost more.
Since more expensive optics usually tend to have a larger max aperture ...
More clearly: that the pictures taken with point-and-shoot cameras are crappy is not the fault of those cameras, and pictures taken at the same time by the same person with a different camera would likely also be crappy.