Yes, very disappointing. I thought it'll be something similar to this YouTube video "Evolution of Electronic Music (1929 - 2019)", which btw I like very much but it's severely lacking due to being only =~ 20 minutes: https://www.youtube.com/watch?v=MqukyEC3qWM

I don't know how accurate the YouTube list is but I never heard of anything prior to Jean Michelle Jarre's Oxygene (about 6 minutes in the list). If It were to compare the list with geological history, before 1976 it's weird Ediacaran biota. And afterwards, suddenly, it's like the Cambrian explosion :)