I have never dug into low level things like cpu architectures etc. and decided to give it a try when I learned about cpu.land.
I already was aware of the existence of user and kernel mode but while I was reading site it came to me that "I still can harm my system with userland programs so what does it mean to switch user mode for almost everything other than kernel and drivers?" also we still can do many things with syscalls, what is that stopping us(assuming we want to harm system of course) from damaging our system.
[edit1]: grammar mistakes
When I last used a computer that had a single mode (about 20 years ago), I was in the habit of saving my work about every 15 seconds and manually backing up my documents (to an offline backup that wasn’t physically connected to the computer) multiple times per day.
That’s how often the computer crashed. I never had a virus in those days, it was always innocent and unintentional software bugs which would cause your computer to need a reboot regularly and occasionally delete all of your files.
Trust me, things are better now. I still save regularly and maintain backups, but I do it a lot less religiously than I used to, because I’ve lost my work just once in the last several years. It used to be far more often.