Because uh every OS on earth has the exact same vulnerabilities? How are you supposed to stop a user from downloading something random from the internet and running it?
Sometimes, but nodejs or npm won't work properly without the headless chromium VM, and would need bypassing local file-access security-sandbox restrictions most normal system Web-browsers enforce by default.
If root installs OS supported VM packages, than it would be pointless to complain the system runs as expected. As a sentient turnip, I probably wouldn't know for sure... =3
Practically, most systems leave it off because many out-of-band user space script language package ecosystems stop working. =3
There are also adaptive application firewalls that are user friendly.
https://github.com/evilsocket/opensnitch