Of course there's more to this than "corpo bad", it's the economic system that drives these businesses to focus on profit over the quality of the user experience--but I think that's the core to all the "corpo bad" arguments when you really boil them down. These websites and services have become so ubiquitous for two reasons:

The first reason, is that people tend towards simplification, if you can give them a centralized location where they can have all their needs met, they prefer it to the effort it takes to use multiple locations/services. A great example is the popularity and convenience of stores like Walmart or Costco where you can do all of your shopping in one quick go. Facebook, Reddit, Twitter, and even YouTube to a lesser degree all offer these one-stop-shop kind-of models by allowing you to connect with a vast amount of people, discuss a large number of topics, and view multiple forms of media. So, unless they have a good reason to remain diversified, people tend towards simplification.

The second reason is also psychological in nature. These companies, (whom we will refer to as FaRT), have designed and redesigned their entire systems to drive up refresh rates, click-through rates, and otherwise increase advertising visibility. In addition to hacking the addiction mechanisms, and the desire for people to feel important, they take it even further using deception and "dark UI". Even when you utilize many of the adblocking systems, for example, FaRT inject advertising content directly into the same stream of other user content(the best example is direct corpo sponsorship of big name YouTube content creators, but at-least that money goes directly to the creators). Plus, advertisers are getting much, much better at disguising this content so that you are less likely to skip it before seeing it.

So it's a two-sided coin, a major part of the problem is that "corpo bad", and now that they're taking it to a degree of harming the public experience for profits (which is why cable television died), it's our responsibility to step out of our comfort zones and show them that we are willing to inconvenience ourselves a little for a better UX.