Spoken like a man who doesn't understand how art and visual design work on a profound level, in my opinion.
You're in the wrong here. It doesn't matter what the original piece, zoomed out and uncropped looked like, because that isn't what is being presented. That’s almost completely irrelevant. What matters is what the cover of the PHB actually looks like. And that is a weird mess, I would say, and I suspect you at least partially agree, given this peculiar line of argument. An art director, himself an artist, made the artistic decision to make (or have made) this crop and this overall design, approve it, and have it printed. He took arguably decent art, and by editing it, changed it into bad art.
Anyone who has worked in actual image editing as a job, or heck, anyone who has done any kind of art involving other people's images has themselves seen that this is something that happens, something that with taste and talent and the right choice of source images, you can generally avoid (though not always). You will, quite rightly, be judged on the final image you deliver, not the source image.
At the very most you might argue that the original artist is more talented than one would credit from looking at the cover of the PHB. I might even concur. But "5Es art" in any honest sense is what 5E actually delivers in actual products, after the art director and editors have been at it. MtG has art director and even tricker space to use art and they do a great job.