noth8ing to do with twitter tbh. that feature just makes perfect sense in particular if you want to keep a note prominent on your profile beyond a flood of notes
Discussion
It makes no sense at all that you consider your "profile" whatever is the twitter-like view of your notes a client happens to be showing.
Your "profile" can be many things in different contexts. It can even include a selection of your favorite notes or something like that. The concept of "pinning" is really specific to Twitter.