It will also be used by quanta usage heavy decks (few Quantum Generators)
I disagree. If you have few Quantum Generators the LAST thing you want is to use a card that slows you down even MORE and WASTES quanta for a lot of time. You'll be heavily outrushed.
If you have few quantum generators you want them to produce more quanta or produce quanta faster than pillars.
Stalling is needed for the first. Rushing is needed for the second.
Yes, but playing Primal Quantum in a deck slows it down considerably until you reach a point where it becomes
broken profitable. Therefore, you will need stalling, not rushing. And the stalls that benefit from lots of quanta are the ones you showed.