this is just not true. the market for new grads is extremely bad. Microsoft could easily invest in more early career people, instead they're hiring more senior H1-Bs.
But a contributing fact is flooding the tech market with H-1B visas spikes labor supply, kills workers' leverage and lets companies cheap out on salaries instead of bidding them up.
The imported worker, on the other hand, is a more efficient and compliant machine. Maybe if we make those youths as poor as the workers we import, they'll eventually learn some gratitude.