I think the basic assumption is some kind of change to the laws of physics and thus transistor frequency scaling otherwise it’s effectively just asking what it was like in the past. So dropping 6GHz 64 bit chips to 300 MHz doesn’t imply everything else is the same and where just using 32bit PII era hardware.

Similarly rather than NVMe 2TB SSD’s at 6000 MB/s we could have 2TB SSD’s at 300 MB/s. Which then opens the door for even more extreme differences.

If the “PIII was a 12 ^core^ CPU at 500 MHz” that’s quote odd by historic standards.