I understand that the production of such "music" usually starts with a "rhythm track" to which other layers are added.
Sort of how baroque music is made then...

There is a really good book of Renaissance and Baroque bass lines you can use to emulate Tin Pan Alley hacks like Monteverdi, Purcell and Bach - Martin Erhardt's "Upon a Ground". I'm slowly working my way through it using the a=415 version of the backing CD.

An unvarying basic rhythmic pattern is also common to the Middle Eastern art music I play every week - usul in Turkish, iqa' in Arabic.

Some of these grumpy-old-man comments remind of an anecdote from a rural autobiography where the writer described talking to an old farmworker who was complaining that you didn't hear birds singing any more. There was a lark swooping and twittering directly over his head throughout the conversation but he was too deaf to notice.