It creates various perverse incentives, so even if it might work if all the involved parties are well-behaved, it pushes the situation towards people not "behav

It creates various perverse incentives, so even if it might work if all the involved parties are well-behaved, it pushes the situation towards people not "behaving well", at which point the proposed system would not get good results. It incentivizes abusive companies to fire people quickly after firing - most companies do it, but some do; and the proposed system would increase that. It incentivizes behind-the-back deals with ex-coworkers, stressing ethics and relationships. It incentivizes inequality - it gives an advantage to people with a wealthy "support network" and creates a barrier to people who don't have one, if a company prefers to do hiring this way.