For the use case of watching a movie?
You seek back a scene or two while watching something when your mind has wandered away and you missed what was going on a few seconds ago. For some non-neurotypical people it's a really common thing to do while watching a longer movie as it may be hard to follow what's going on otherwise.
Unacceptable for what use-case? I had assumed this was somewhat intentional on Netflix's part, or at least not a priority for them.