I really don't like this euphemism. When I read this I know what you mean[0] but I wish this meaning wasn't tied to leaving the office at 5pm. If someone's effective in their role, why should they be judged on what time they leave? This mentality doesn't encourage people to work harder or be better employees, it only encourages them to stay later. That eats into their free time every day, giving them less opportunity to relax and recharge and probably causing them to become less productive and more prone to burnout in the long run.
If I can get my job done by 4pm every day then don't force me to sit at my desk until 6pm to keep up appearances. Either let me go home or help me fill my time by offering me more work (and if I'm highly productive, more compensation).
[0] The person is only putting in the bare minimum effort, has no interest in personal development, is more interested in the paycheck than craftsmanship and professionalism, etc.