I love that analogy "take a telescope to a fruit bearing tree, point at the roots and say look its sucking out all the nutrients from the soil."
But, can we say that H1B and immigration is what fueled the current boom. Or maybe it just went along for the ride.
If there was no H1B program in the US, I would guess that Silicon Valley would be in Hong Kong instead of California.
It is a fact that many immigrants have played a pivotal/transformative roles in many different industries and their booms, nothing as great as the tech boom though. It is one of the few core engines of US staying on the frontier, but not the only engine.