Sure they could have pushed out a VR game every year for the last 5 years to maybe get to the same level of interaction fluidity but they would all feel subpar, not quite there, like the vast majority of other VR games.
Valves strength is that they a have a structure that allows experimentation without a hard deadline, they can afford to throw millions at the wall and see what sticks. This allows themw to take a decade between large, ground breaking projects. They're not beholden to YoY or QoQ growth.
They've had what? Two duds in 20+ years? Not bad when you consider the rest of their output are beloved classics.
Granted they have a good few money printing machines to help them work like this but I would argue that they have these money printing machines because they have the ability to experiment, because of their structure.
From the outside, all we see is very few games being produced. From the inside, its far more complex; something like a Dark Decade for Valve where even they weren't sure what they should be working on. Hundreds of failed prototypes and ideas. Major technical issues with Source 2 that took years to fix. L4D3 was under development, but ran into huge scope creep (full open world with variable length days depending on time of year and hemisphere, variable tides based on moon cycle, crazy stuff like that). They were working on a tech showcase codenamed ARTI/Artifact using a brand new voxel-based game engine separate from Source (and after the game was canceled, the name was taken and used for the now-released Dota 2 Card Game).