I have said this before here and I will do that again. What hurts the market is L1 visa. H1 visa holders are almost in the same boat as local talent. Why? Because there is a government dictated minimum prevailaing wage that companies have to adhere to. I am yet to meet an H1B who is earning less than his/her peers (within an area, experience, skillset and education).
However, I have met a lot of L1 visa holders (primarily from India) who come here from companies like Wipro, TCS, Cognizant, IBM, Microsoft etc. who are paid lower wages because there is no such scrutiny with L1 visas. Lumping both visas in the same category is a huge mistake.