L-systems were proposed for music even earlier. Here's a link to an article from 1986: https://quod.lib.umich.edu/cgi/p/pod/dod-idx/score-generatio...

It definitely is not a glorified PRNG. The idea is that you can create patterns that have both variety and repetition with them. I don't like the results, generally, but they are not random.

Prusinkiewicz indeed did important work on L-systems and music in the eighties, but the use of generative grammars and rewriting systems in music dates back at least to the sixties. The reslts of such approaches are not random, but "pseudo random", as written. Also the term "fractal noise" is used in this context.