Hey @herman_munster - UI/UX is often very subjective, so I will explain my thought process here.
When you are watching a show and you want to head back to the home screen, the most efficient way is to “mash” the back button. However, there is not always the same amount of button presses to get back to the home screen, depending on how you started the show, how many seasons there are, etc. If you start the show from the CW row, you only need to click back twice to get to the homescreen, but if you navigate to the show via Library → Season → Episode, you need to hit the back button 3 times. So half the time I end up exiting the app while mashing the back button to try to get back to the home screen.
The other option of navigating to the sidebar and clicking the home icon can be a pain/is not intuitive for certain end users depending on where you are within the Plex UI. As an example, say you just finished watching The Office Season 6 and you want to watch something else. By default when you are done watching that episode, you will end up with that episode “selected” and you are in the Season view. So you are on S6E26. A lot of people will start navigating “left” and will end up scrolling through episodes until they can finally “click left” and expand the sidebar. This results in 28 clicks to get back to the home screen.
The other option is obviously to go up to the Season selection screen at the top and “click left” until you get to the sidebar there. That requires 5-7 clicks. The last option (which I actually just found while writing this) is to go DOWN to the play episode controls and then you can click left from there to the sidebar. This method isn’t intuitive to me, I’m not sure why, but does result in the least amount of clicks (apart from the back button - this ties the back button in terms of number of clicks.)
Disregarding number of clicks for a moment, it is infinitely easier to just mash the back button without thinking than it is to navigate “properly” to the home screen. I have spent thousands of hours and dollars on my Plex setup, I basically never want to leave the Plex app on my Shield, and if I do, I will hit the dedicated “home” button on the remote.
To your comments regarding “apps that don’t prompt for exit confirmation” - I was merely pointing out that prompting the user if they want to exit is not “illegal” as @anon18523487 was alluding to. There isn’t a “right” or “wrong” here, this is just a suggestion.
Lastly, to your point of Roku doing it “wrong” is also incredibly subjective, and I am not interested in right or wrong, I am merely interested in feature parity. All clients should behave the same in terms of general UX, I am sure we can agree on that. Especially “TV” based clients. Given that the Roku client was developed a full 2 years before Plex started developing on Android(per forum posts - Plex for Roku thread started in 2011, whereas Plex for Android thread started in 2013), and that other Plex apps (including the now deprecated PlexHomeTheater and the new Plex HTPC application) are all “prompting for user exit…” Well, I’ll just leave that to up to your interpretation.