The better way is to use Qubes OS for security through isolation. You then use hardware virtualization to isolate untrusted application (including browsers) from the rest of system. Doesn't work on mobile though.
Was it ever robust? Or just that there weren't yet so many exploits?
Qubes OS v4+ does not use typical software virtualization methods. VT-d hardware virtualization it uses was broken only once, and it was done by the Qubes founder: https://en.wikipedia.org/wiki/Blue_Pill_(software)