Your insertion of the word "naive" makes this difficult to refute. But if I may rephrase by removing that word, I do think that loyal employees exist. I've been with my current employer 14 years with no plans to leave (as have the other 3 managers in my area, plus many employees). My wife has been in her company for 10 years.
There's much more to having a job you enjoy than just pay. Having one free of politics (as is my office) is important to me. Having a team that one gels with is also very important. I'm spending half of my waking life at work: I want to enjoy it.
But "loyal"? This is not rational. You should never be more loyal to some party than that party is to you. If you are then you've been indoctrinated. You've been had. It's fine to work somewhere a long time because you feel it's currently the best place to meet your overall objectives. It's not ok to work somewhere because "you owe them" or "they've been good to me in the past".
Being somewhere 14 years is certainly an "employee smell" if you will. Usually when someone stays that long it's because they have a misplaced sense of "family", believe their market value to be low (they could be correct), etc., etc. Not because they think it's the best overall deal out there.