Earlier quoted context omitted.
If a company can't recruit an immigrant worker on a visa they'll try recruit one of the currently unemployed local developers on the exact same package the immigrant would have been on. That has no impact on wages. If the job required a unique talent that would only have been possible to fill with an exceptionally talented immigrant worker then the job won't be filled, and the company will be consequently less compet…
Surely if companies are desperate for developers, there would be very few unemployed developers.
This is actually one of the tech industries biggest challenges - how do you drive the cost of products down to compete in the marketplace when producing software costs so much due to high wages. The simplest answer is to drive wages down by recruiting immigrants. The long term answer is increase the pool of available labor by pushing for children to learn to code at school.