But once you do discover them, they're so much better than equivalent functionality on other media devices. Same asking Siri "What did they say?" to trigger brief subtitles.

And I disagree that they're "completely" undiscoverable... if you rest your thumb on the remote, skip forward/back glyphs appear on-screen and indicate the functionality if you were to click.

Don't you just click either side of the remote? A hint shows up on the screen if you hold your finger there.