It's more a question of Amdahl's law: the introduction of SSDs brought I/O latencies from the 5 to 10 milliseconds of HDDs down to tens to hundreds of microseco

It's more a question of Amdahl's law: the introduction of SSDs brought I/O latencies from the 5 to 10 milliseconds of HDDs down to tens to hundreds of microseconds. Going from tens of microseconds to 100-200 nanoseconds is much less of an improvement for most general purpose workloads.