Well, yes but no:

The Z80 took 3 cycles to load from memory. A register to register transfer took 4 cycles (including fetching the instruction). Only one of those cycles was instruction execution.

I think the only reasonably mainstream scenario where the CPU would be significantly slower than memory would be the serial CPU designs such as the PDP-8/s.

That said, at the time people were doing cool stuff with 8-bit CPUs, they weren't running software remotely like what we're discussing here. That would have been done on a VAX, which had instruction and data caches.

What really happened, that the article is alluding to is that memory didn't get much faster in absolute terms since the 1980s. CPUs on the other hand did.

E.g. in the 1980s we had 60ns DRAM. Today DDR5 I believe allows about 10ns random access reads best case (6X). Over the same period CPU clock speeds have increased from about 8MHz to 5GHz (600X).