But then you would have issues with how to evaluate the immigrant. You may say degree, work history, other achievements, etc but those are already being used as qualifiers in the current system, in addition to the job requirements. So any attempts at decoupling immigration from employment would be seen as "open border" by many politicians and their bases, i.e. not going to be a reality ever.

If even a law trying to let US-educated PhDs getting an H1B easier (just to work, not GC) get blocked, you know how anti-immigration the current political climate is.