I am old, too, old enough to remember sending personal data over plain http with no encryption and needing to do a full wipe of Windows 98/XP machines on a periodic schedule just to keep viruses and malware off of them.
The idea that application A can just have full blown disk access and slurp up your tax returns or something was always a pretty crazy security posture. It just so happened that an honor system kind of almost sort of worked for a while.
You can’t really do an honor system when people are running artificial intelligence systems that have no concept of morality with full disk access.
Realistically we’re never going to be free of rowhammer and meltdown type attacks. Trying to prevent programs running on a computer from having full control of it just promotes a false sense of security.