Maybe that is the downside of the general policy of abstraction that Devs use, that software should be made to look as simple as possible, and all the apparently "unnecessary intricacies"(which could have disastrous effects) should be dumped under the hood.
The point of abstraction isn’t to hide information from you. The point of (properly done) abstraction is to allow you to work without having to worry about the details.
Abstraction has nothing to do with this. The problem is the side effects of social media. Even if Facebook open source their algorithms, I doubt anyone could have conclusively predicted this. We only know all this because of empirical sampling of the user population.