I only see an overall labor shortage in tech fields. I’ve never heard of even mediocre developers having trouble finding work, except for a brief period in the early 2000s. I think wage suppression is only contributed to in very small part by the oft-exploited labor coming here from overseas on the H1-B and similar programs. I see this as trying to make the program function more according to its stated intention and bring in skilled labor.
It's the mediocre developers or developers in areas where the overwhelming majority of the jobs are mediocre that are hurt by this. Generally speaking they're not being replaced with better workers, they're being replaced with cheaper foreign mediocre workers.
Wages are flat due to inadequate wealth redistribution leading to a sluggish, understimulated economy. The minimum wage is many years overdue for a major increase - people at the bottom of the wage scale spend virtually all their income back into the economy. Billionaires hoarding enormous sums of US generated wealth in overseas banks do not.