It is not alarming about tech visas
Shane, your analysis is good comparing both visas. But L1 usage is much restricted for companies and path to green card is faster, so they quickly loose the workers. Moreover both visas are getting expensive and lot of administrative burden on the companies, so they first prefer local like green card, citizens in most of the jobs, only hard jobs like programmers sometine goes to these visas or graduates from colleges including foreign students, It is not alarming as you described.
Regarding the the usage of these visas by these tech companies, it is about their cost/budget and quality levels.
Instead of moving abroad theya are atleast trying workout something by staying, that way it is better.