They’ll say they just want quality employees, but interview with them and they’ll care little about your skills. They always want to know how much business your clients brought you, seek traders with a good "track record", ask how much profit you made, with the implied understanding that you will bring them that business.
IMO it’s fair to strike a balance, so companies can earn some returns on R&D, and employees can get fairly paid. Your employer shouldn’t lock you out of working forever, nor should competitors be able to hire away instantly by paying $x+1.