The difference is noticable, the modern laptops are subjectively perceived by users as faster, even if they have slower CPUs.

Also, they do not have a problem with Electron apps. for most people, they are just apps like anythig else, and do not perceive any performance problems with them.

That is mostly due to SSDs, which can also be fitted perfectly well to older laptops, SATA has been standard for a long time now.

And where did Electron apps come into the discussion?

The difference between NVME SSD and SATA SSD is like between classic HDD and SATA SSD. It has to; NVME can push 4GBps, SATA3 only 600MBps.

Even the Apple 2015 M.2 drives, which are "only" AHCI, but with much deeper queue (i.e. nonstandard), can do 1.something GBps and the difference compared to standard SATA SSD is noticable by normal users.

Electron apps are something normal people use and some of them compain about the speed/lag/memory usage. Usually those with older computers, who think nothing changed in the last years ;).

But for most people, that speed difference is purely academic, and doesn't actually benefit them. Sure, if you're compiling stuff or otherwise moving around a lot of data, it matters. But for most people, it's just some numbers on a spec sheet.

If you do not perceive a difference between HDD and SATA SDD, then you won't perceive the difference between SATA and NVME SSD either, that true.

If you do the first, you will do also the second. It makes a difference even when launching Excel or Firefox.

There is a definite difference between old-fashioned spinning rust and SSD.

Between SATA SSD and PCIe? Sure, for extremely IO-heavy tasks there's a difference to be felt, but not really in everyday use.