This is exactly it. I'm building https://getartemis.app, which, as you can see on the home page, has an automatic muted video playing of the demonstration of the product. Most people without such autoplay will not want to click play, and thus my email sign-ups will decrease, which is the same rationale as every other site with autoplaying videos.

When I first learned Chrome disabled autoplaying videos, I converted my video, which was around 500 kB, to a GIF, which was now 30 MB, with a noticeable decrease in smoothness and quality. Companies will not stop autoplaying videos, they will merely find other ways around it, because autoplaying videos work for the vast majority of users.