I think back to many tutorials and code snippets in which I have seen variables, functions, and files with "my" or "my_" prepended. What is the origin of this convention?
Origin? ...I think that comes from simple human interest in taking topics out of the specific and into a more general context, in that, at least when I do this myself (which is mostly every time I share ANY code in a public forum), I, as the old Dragnet TV program used to say "change the names to protect the innocent." It's not any more complicated than that!
This is ESPECIALLY true of people asking questions in the Stack Exchange community: MOST of us work in environments where whatever we're working on is at least SOMEWHAT concerned about privacy; we don't want to inadvertently, much less intentionally, share information that we may very well have non-disclosure agreements covering! This could be code we're writing for a client or for a corporation, etc...
Don't over-think it!