gotta figure out where would the button go, the UI is quite crowded already. But otherwise it could work.
Tough the app should save the position in the field today. It only doesn't save when the user or Android kills the app and restarts it.
Discussion
Well, if I start scrolling and close it I have to scroll down to wherever I was before closing. Maybe I need to change a setting on my phone.
Sometimes it will jump back to the top of the feed if I reply or read all of the replies on a thread.
I think a bookmark symbol at the top would work. Maybe only have it for the all follows option?