My job in a tech startup in NYC is 9-5. We are on call on rotation, which usually means two or so weeks a year. I don't look at Slack or email after 5pm nor do I have any notifications on my phone for any work-related app (just Slack for now).

It really hasn't affected my career - I just got a raise/promotion actually. My experience is that the "I love to work!" type of employees just get more work assigned to them instead of rewards.