Earlier quoted context omitted.
It's because a website requires an active will to be maintained online, while a movie, while released, just sit here on its medium.
Incredibly the more features and bloat one adds to the pages the less likely it is to stay functional/not be hacked etc. The first iterations of the Web where nearly perfect for information retrieval / linking of actual information. We spent the last 20 years adding videos and adding tons of crap that make the whole experience worse and are quite detrimental to the signal to noise ratio on most websites.
Just like TV shows that use frequent animated overlays, and ever-changing camera angles. If things stop moving, we reach for our smartphones.