I feel like that, as a baseline, most people are generally positive or at the very least neutral when talking about something. So when you want to stand out and do something different and/or interesting, one of the easiest way to achieve this is to jump to negativity.
But there are other ways for people to stand out with something different and interesting... I've come to realize that I love deep dives into something I enjoy. I love Mark Brown's videos for taking a very close look at video game mechanics and Legend of Zelda levels. I love Captain Disillusion for his thorough analyses of 3D effects used in fake viral videos. Tim Rogers of Kotaku makes amazingly thorough and deep reviews of games every so often, often bringing his insight and personal experiences as a Japanese game dev into it. I will watch pretty much anything from those guys, even if I'm not interested in the subject they're talking about. The problem is that these videos take a lot of time to make due to research, they require a level of talent that not everyone has, AND they're also very niche.
Basically, I can see how it can be very hard to stand out from the crowd when you're doing daily or very frequent videos, and how negativity is a very easy way for anyone to gain visibility. I can see how for those starting out on YouTube, building up their talent, and/or trying to find their voice would jump to that in order to find an audience, and then sticking with it because that's just what works.
Not to speak any ill of Sterling, though... I really like his videos and appreciate his opinions on a lot of things, but I find myself carefully picking and choosing which of his videos to watch. I just can't personally watch everything of his, because it can get way too overwhelming for me. (I also neglect to enter a lot of threads here for similar reasons, to be honest.)