They existed before iPod, they just didnt get the marketing blitz Apple did. Cowon comes to mind, and had much better quality audio.

I did some research on this, because I was a big fan of MP3 players in the late 90s early 2000s and never heard of them. Turns out that the only Cowon Mp3 player I could find from around the iPod launch was the iAudio CW200, which had a capacity of 256MB.

This explains why I had never heard of it, as I was shopping for HDD-based players that could hold my entire library(I was looking at PJB, Nomad, Archos, etc).

Sorry but this illustrates OP's point. The iPod was the smallest HDD-based player on the market for years, all the other HDD players were chunky and could barely fit in a pocket. All the flash-based players had pitiful capacity. It wasn't that there were no MP3 players, it was that all the products had compromises that made them not ready for mass adoption.

While OP is overstating some things, your counter examples are rife with oversights like this.

As an example you are badmouthing Apple's "low resolution displays", while missing the fact that the MacBook Pro was the first ever mass market high dpi laptop. Ironically Samsung had produced a limited production laptop with a similar screen, but because Samsung lacks focus and had 1000 different laptop SKUs, they didn't make it a premiere feature of their brand, instead Apple simply bought out Samsung's entire manufacturing capacity for years and put them in their laptops.

This is the pattern. There are interesting technologies, but they are in products with mediocre design or appeal, and are not mass produced. Apple identifies these technologies, optimizes them, integrates them, ensures that there is a good user experience, makes a million of them, makes a billion on that, then changes the entire landscape of the market they entered by virtue of their success.