I'm not saying it's good or bad at brain drain, I'm just saying without knowing how many people overseas are worth "draining" that's not an argument.
The program might have been designed for this, sold as this, but it's definitely not used for that anymore.
H1B was created in 1990, that's when Russia (and ex-USSR in general) had a lot of idle brains that wouldn't mind moving to the US. Today isn't 1990 tho.