It's just safer/easier to use a throwaway. I have these opinions in real life, but I try not to be too controversial in writing.
As meta comment though, I don't think anything you said is necessarily controversial, it's just debatable. Obviously you need to gauge the potential fallout on your own life, but the comments themselves are fairly innocuous.
It's just a habit of mine to make a throwaway for anything potentially controversial. It really wouldn't be too big if a deal if my identity was connected to any of my throwaways. It just makes me feel safer.
But in general, I don't doubt that these things are well intended and not malicious. In my case, my complaint isn't that Facebook is malicious or intentional. It's more of a negligence or gross negligence point.
[Edited for clarity]