Actually, I believe it’s quite the opposite, in the past memory and storage were very slow so the CPU had to wait for them a lot. Now, thanks to improvements in memories and especially in storage, the CPU does not wait for them for long, and nowadays it’s the single-core performance that matters. Meanwhile, CPU tech did not improve so fast due to hitting the ceiling on single-core. In the past, manufacturers were just keep increasing the processor frequencies. At some point (around 5GHz) they realized they couldn’t keep increasing it, so processor gains diminished and focused on multi-core optimizations.
I have a laptop that scores 1700 on single-thread performance, with 20GB RAM and SSD, and it’s not pleasant for me to work on it.
Regardless of whether it is fast enough or not, it can’t compete with Macbook Air with this performance, not even at half the price.