In the past, user manuals often explained every single aspect. However, that brought its own problems. Things would be over-described and written without the poor user in mind, probably by electronics engineers based in the country where the product was developed and then translated very literally into a form of English that doesn't bear much resemblance to how 'normal' people communicate.
These were simple devices from a now bygone era where each product would perform one main function, and they'd do it with no Bluetooth, no Wi-Fi connectivity, no operating system upgrades or file format conversions. Yet despite this, the user experience was affected by over-complicated instructions.
This was years before Apple's iPod shook up the portable music sector with its celebrated ease of use, which was in turn replaced by smartphones and streaming services like Spotify. Now the equivalent of a programmable CD playback mode can be a playlist compiled from almost any pieces of music ever made, and it's not too hard for anyone to get to grips with. It goes to show how a jargon-free listening experience can truly hit the right note.