Understandable. A counter would be that you can't expect to retain someone who's really good if this is your habit, but the counter to that would be that you can make it up if you're really cultivating a culture of hiring high quality job-hoppers.
It's the difference between taking one extended-release medication or taking a new pill every hour for the same effect. With the ER, if you get a dud, you're in trouble all day. With short-lived medication, duds can be a big problem in the short term but overall you can still be getting better.
I’ve seen teams get screwed over by someone parachuting in to deliver v1 with shiny new tech and getting a pat on the back ($$) for a job well done. Fast forward 6-12 months and you realize the new tech debt is as bad or worse as the old tech debt.
That said, stagnation and sticking with Blub can also bring its own set of issues.
Fast forward 12 months and we have a terrible, complex, non-scalable, system, which should have just been a really simple REST service but instead we just have another point of failure.
Oh, and they quit so have no idea that their designs were trash.
They also bring in a lot of change for change sake because they don't know the current systems.
I don't know of any employers who would admit to deliberately rewarding job-hopping outside the company[1], but I suspect that's out of concern for potential negative consequences of admitting to the practice, not because they don't do it intentionally.
Hiring skilled job-hoppers often makes a lot of sense. They bring in knowledge and experience of things that worked (or didn't) in other organizations. It can be a great way to avoid getting stuck in local maximums, and avoid repeating mistakes others have already made.
[1] At least one previous employer deliberately rewarded job-hopping between roles internally, because it gave people a much wider base of knowledge and promoted empathy between people in different parts of the company.