I have not found that to be true, maybe due to company culture. Both my manager and our best engineer left my current company and returned, one after 2 years an

I have not found that to be true, maybe due to company culture. Both my manager and our best engineer left my current company and returned, one after 2 years and the other have just 3 months. Both have been subsequently promoted. Our industry is not small but we all know people in rival companies (semi-conductor, EU) and a lot of management have left to work for competitors at one point and returned. Unless you work for a seriously petty manager or an unprofessional family size company that holds grudges, leaving and returning should not be a big deal.