The blame is somewhat misguided: what's blame to here is cost-cutting, not printing on demand. If you're willing to pay, you can get POD books that, certainly to the untrained enough, are indistinguishable from "real" books.
For example, Lulu's hardcover books with linen wrap, dust jacket, "premium" B&W printing with 60# uncoated cream look pretty darn good: https://www.lulu.com/pricing
Hi author here. I've bought a probability textbook from Lulu and it was fine. I don't blame POD but rather misinformation and poor quality. Almost all the POD books I've received from Amazon are very distinguishable from real books.
Yeah, I'm leaning towards that conclusion as well. While I don't publish my writings, I have a few friends who do. The stuff that comes from Lulu, even the cheapest "models", is honestly fine. The ones from Amazon, not so much.
Of course if you typeset and edit your book like a moron, that's going to impact the quality, but this has nothing to do with POD.