I don't disagree entirely. . .and in my previous life as a manager. . .and before that, as a team lead. . .I encouraged everyone to keep growing professionally and to keep their resume updated - and to never assume that they could stay forever and/or leave on their own terms. I told them that I did and that I just considered it sound professional advice, no matter how much we loved and respected each other, the organization's mission, etc. On the other hand, I do have loyalty to any co-workers and managers that I genuinely like AND respect. Not to the point that I would sacrifice myself professionally for them, but I do have loyalty. And in past lives, I've told those that I trusted to be mum and professional when I was starting to look for another position - even if was just another position in the same organization and just to give them a heads-up.
As a matter of fact, my peer in our organization left a few months ago. She felt guilty, knowing that my life would almost immediately become more difficult, but I stressed to her to do what was best for her. She started to waver when management asked her to delay her departure - I reiterated that she should not worry about me or management. She was loyal - which I appreciated. And I was loyal and shoved her out the door.
I usually let people I mentor/manage know that they are business for themself. They need to keep the resume polished, the salary figures down cold, the skills fresh. If we all understand that we're in all in business together, contracted to do high quality work together, then certain ground rules are understood and we all can get along fine without manipulative koolaid.
As a matter of fact, my peer in our organization left a few months ago. She felt guilty, knowing that my life would almost immediately become more difficult, but I stressed to her to do what was best for her. She started to waver when management asked her to delay her departure - I reiterated that she should not worry about me or management. She was loyal - which I appreciated. And I was loyal and shoved her out the door.