Just because something is popular does not necessarily mean it is sensible (people use Beats headphones to listen to .mp3s, for Christ's sake).
Canon's DSLR video capabilities were kind of impressive when the 5DmkII was released, but even then it was (and still is) plagued with flaws, and in some respects has gotten worse (overbearing AA filter on the 5DmkIII).
Of course, it should go without saying that none of these issues should have any impact on the integrity of your art. Your support and lighting matter more than your camera body, which in all reality is probably one of the least important pieces of equipment; as long as it meets some minimum, rudimentary criteria, it will enable you to do your job. Amazing image quality alone means nothing (care to explain why 99% of RED videos online are garbage?), while some of the best videos I've ever seen have had mediocre or terrible image quality. How does that work? Your technological means of communicating an artistic concept, and that artistic concept itself, are entirely separate. You can polish a turd all you want, but at the end of the day it's still a turd.
But if we must step into a vacuum for the sake of technological discourse, here's the reality: Canon's DSLR video capabilities have been far surpassed by numerous camera manufacturers for a fraction of the price. To consider Canon as a competitor at this point is laughable.