The japanese tried to build massively parallel computers back in the 80s. The project ultimately failed because the performance of normal CPUs continued to improve. It looks like we are once again in an age where parallelism seems to be the only way out: CPUs have hit a thermal ceiling, speculative execution has led to vulnerabilities... Given the popularity of today's GPUs and their applications, I'd say the 5th generation computer project was ahead of its time.

https://en.wikipedia.org/wiki/Fifth_generation_computer