It depends on how small, and how swarm-y. If the function is hilariously simple, and improves readability (like a premade getter for an alist or cons based structure in lisp), just do it. If it's pretty big, and you'll never reuse it... No. If you must, keep it local.
Even if you don't reuse a function it still encapsulates certain things. By looking at the name you know what it does (self-documenting-code). The interface tells you what variables it depends on. And finally it logically segregates your code.
I think the real reason people don't like small function is simply code navigations - which honestly is a poor excuse. That's an editor/IDE problem
Yes, but encapsulation isn't always a good thing: it lessens your awareness of what's happening within the encapsulated environment. This can lead to bugs.
