However, if someone has generally changed jobs every year or two and I wouldn't hire someone who I knew with certainty would only stay that long, I might think I'm special enough that I can keep them around. But I'd probably be wrong.
I can only speak for myself but so much of my job hopping is geared towards both getting more money but just as importantly trying to find an environment I really like. I want to find work that is fulfilling and that does not make me dread Mondays. I have reached a level financially where while I can always use more I make more than I ever reasonably expected to make and I am making far far less than many on here. My years are precious I want to spend them somewhere that I like both the people I work with and the work I do.
Yes you have figured out the secret (tm) in my opinion. Sturgeon's law applies to tech which is to say 90% of it is crap. Don't waste your time with that 90% and if you find yourself in one of those positions feel no guilt whatsoever running away as fast as you can.
And that's the thing, it's okay with me if I'm wrong. Or as I responded to a doctor who asked a similar question: "Do all your patients live?" It's not a question of being special to me, it's a challenge to figure out what will make them stick around and make the company money and it's usually strongly correlated in my experience.
But the grandparent comment assumes that you can keep a certain percentage of engineers you want to by making them an offer that gets them to stick around.
However, if someone has generally changed jobs every year or two and I wouldn't hire someone who I knew with certainty would only stay that long, I might think I'm special enough that I can keep them around. But I'd probably be wrong.