Loyalty has always been treated as a weakness and a strength. Your loyalty is my strength.

The problem is that loyalty is one of those words that is so emotionally charged that doesn't really mean anything concrete anymore.

If you define loyalty as ignoring short term potential self-interest by leaving/betraying/not-doing-overtime in favor of the long term value you will receive from the relationship, then, even if you may be betrayed in return anyway, it's not really weakness - you just made a mistake.

If you know you're getting a bad deal, and you predict it's not going to get better in the long term, and you stay anyway, you're not "loyal", you're weak.