Thats absolute nonsense across the board, it might be true in some circumstances but not as a blanket rule
I have a job that is hugely in demand but not desirable in the UK, its not transferrable to another country without learning intricate language skills, to the level where abstract concepts, human development, legal concepts could be described and then also requalifying in that country and learning the equivalent law
I dont have the language skills to learn a new language to that level and neither is my job one where I would be able to get an employer sponsoring me to move. In order to qualify I need experience, in order to have experience I would need a sponsor, cant get a sponsor unless Im qualified.