VVT does achieve the goal too, if you close the valves later you’ll def. have a reduced compression ratio. That helps avoid premature ignition through compression. (Well, duh…)

But igniting the mixture earlier also helps, probably won’t work for engines that are to high in compression.

And forced induction engines with electronic boost control could lower boost pressure, that would also help avoid knock.

At least that’s my understanding…

VVT isn’t really needed for that though, advancing spark can be enough to avoid knock. Although I’m not sure if an engine like that would receive benefits from premium.