The world could run on older hardware if software optimization was a priority

If dynamic array bounds checking cost 5% (narrator: it is far less than that), and we turned it on everywhere, we could have computers that are just a mere 950X faster.

If you went back in time to 1980 and offered the following choice:

I'll give you a computer that runs 950X faster and doesn't have a huge class of memory safety vulnerabilities, and you can debug your programs orders of magnitude more easily, or you can have a computer that runs 1000X faster and software will be just as buggy, or worse, and debugging will be even more of a nightmare.

People would have their minds blown at 950X. You wouldn't even have to offer 1000X. But guess what we chose...

Personally I think the 1000Xers kinda ruined things for the rest of us.

Security through compartmentalization approach actually works. Compare the number of CVEs of your favorite OS with those for Qubes OS: https://www.qubes-os.org/security/qsb/

tl;dr: Qubes security relies on Xen, which is quite popular. But even Xen has more vulnerabilities than Qubes thanks to a clever design: https://www.qubes-os.org/security/xsa/#statistics.