I do think the new account auto-subscribe thing has a lot to do with some of the massive channels that have popped up over the recent years. But, the steady views might also have to do with most of their views coming from the search engine. I only get a small fraction of views from subscribers in comparison to views from the search engine. I bet that happens to a lot of big YouTubers, too. Although unsubscribed people are finding their videos and watching them (perhaps subscribing, too), the number of views from subscribers is generally much much smaller than views from other sources. If you have a lot of videos that people can find in a search, then the views from search engines are sort of "diluted" between the videos, and only subscribers tend to watch the new content. That will make it look like you are gaining a lot of subscribers, but your views aren't changing much because the fraction of views from subscribers is so much smaller than the fraction of views from the search engine.