Actually, Betamax also failed due to one important but trivial flaw: you couldn't put long movies on a single video casette. They fixed this many years later, but by that time it was too late.

As for EOS, the tech is only half the story: the community the other half. Also, C++ may be a mainstream language, but it is not easy to work with, and actually has a much smaller hobbiest userbase than Python or JavaScript.

Just my 2 cents as a CS academic. Hope it's of any use :).