And while it is inefficient if a company has to constantly retrain employees, overall you can have a more efficient market when people are given options, since employees can find the best fit. If you're working a job that isn't the best possible fit (something that's harder to find when your limited by time and resources) that's worse overall for the economy.
Of course there's more nuance here, but this is the core debate of unemployment payments. More unemployment benefits incentivizes people to stay unemployed longer (bad), but when they do find eventually find employment, it's usually better employment (very good).
Maybe "a competitive labor market" doesn't, but "job hopping" does. That is, in fact, the definitional meaning of job hopping. They specifically made the claim about "job hopping" as pertains to a mechanism for achieving wages. This is incompatible with finding an optimal fit -- even if you found your optimal fit, you would essentially be taking a massive wage cut to stay at your optimal fit job for more than a couple of years, if job hopping is the chosen mechanism for society-wide wage growth. I was responding to the claim that was made about job hopping, not some other claim about competitive labor markets.
Job hopping is the result of competition in the labor market, and while some may find it unfulfilling, that is usually the exception, and macroeconomically speaking, more job hopping can be really good for the overall market. That's all I was saying, though I forgot to mention how competition in the labor market relates.
My definition of job hopping is to switch jobs continually until you find the right fit, the right fit including wages as a factor among many others. I suspect that your definition means jumping jobs arbitrarily for the highest wage. In that case you are right that job hopping is bad, and it's my fault for confusing job hopping as wage increasing mechanism vs job hopping in general.
The reason for all of [job hopping, fluid labor markets, bankruptcy, startup formation, inflation] is because the world doesn't stay the same. Desires change. New technologies are invented. Resources get depleted, and substitutes need to be found. Bottlenecks emerge. Old people die, and young people are born.
Changing wages and periodic layoffs are ways of adapting the jobs that people do to the new realities of which jobs need to be done.
If your mindset is "The economy is an incredibly dynamic, living thing whose purpose is to satisfy the consumer desires of the moment", then job-hopping can be all of very satisfying, very lucrative, and very purposeful. Your purpose is to do whatever is most needed. You don't get attached to any one task, but treat yourself as malleable and adaptable, and think of your past roles as a portfolio of skills and experiences that you can draw on to meet new challenges. You could describe your approach to work as "Work is something I do, not what I am."
If your mindset is "The economy is the society that I grew up in, and I'm seeking my place in it, and then I want a role where I can grow and build expertise", this is extremely unsettling. You view your job as an identity, a part of yourself. To leave that job is to leave a part of your identity behind, and to be fired or laid off is to have a part of your identity ripped away. And so you'll fight hard (and take many poor bargains) to avoid being put in that situation. It's not simply a matter of economics; it's a matter of being and belonging. Work is not just what you do, it is who you are.
Commerce vs. Guardian syndrome [1], or growth vs. fixed mindset [2]. There isn't really a right answer, but American culture, society, and business favors commerce syndrome over guardian syndrome, while many other cultures (really, most of the rest of the world) is the opposite.
[1] https://jebkinnison.com/2016/04/29/jane-jacobs-monstrous-hyb...
[2] https://online.hbs.edu/blog/post/growth-mindset-vs-fixed-min...
A certain amount of churn is good on the national or even global level, because it moves knowledge between companies. Probably not great for the company you depart, but great for the company you arrive at.
Or maybe it was because I was younger then?
Stayed at Google over a decade and it wasn't quite the same, particular when working with people in distant offices.