Root and then branches. Ever since books happened, we categorize and navigate information through the same system. Dictionaries follow this rule: letter B, the root. Words starting with B, branches.
During the days of the command line, computers used a tree representation for things. As a kid, it was easy to understand: up and down branches where my stuff is, the root where operating system files were.
Then GUI happened. At first not really a big change, just a graphic tree. But then, shortcuts. Most people still don’t get where their stuff is because of that mapping shit that confuses them.
Then the internet happened. It followed the tree rule too: tree.com/branches. BUT. For some fucking weird reason, engineers thought that it would be super cool to have something that means the exact same but completely destroys the consistency: branches.tree.com
They allowed the branch to be “under” the root so that people really don’t get confused…
in the same vein: websites end with a dot whatever, right? Nope! Let’s have .co.uk and .or.jp (yeah in Japan .org are .or), let’s have weird exceptions to help people out! Medium introduced another stupid thing: instead of having medium.com/user they have a medium.com/@user because fuck your face that’s why. Fuck that website.
In the end, those design decisions mess up a consistent system that we all knew, for no other reason than we can mess up something that worked fine. And subdomain.domain will never not sound weird or fishy.
And so of course people stay on Facebook. Engineers, you suck at design consistency. But more importantly, you drive people away from independence. You foster their weaknesses with your decisions.