The people who are closest to and most affected by problems are the best suited to solve them. If you hire a fleet of people who don't care about solving those problems, they won't get solved. You hire a fleet of people who give a shit day in and day out, you're going to get those nagging issues that, in the long run, cost you the most.
Those companies that think that boots on the ground are replaceable in any industry overestimate the importance of management.
I rely on my people to keep me abreast of the issues, as a manager, that I need to be aware of. I expect them to fix the issues that are within their power to fix and escalate the rest of them.
"People that don't love what they're doing, that don't like what they're doing, they have problems. They're not enjoying it, they're not putting in the extra hours, they're not being creative in trying to find new solutions. So when you love something and you're passionate about it, you put the extra effort into it naturally, you try and get creative with it naturally, and you end up more successful naturally because it's something that you care about."
There are booming industries where the boom mostly floats top executive boats, though. Ask an Uber driver, or an Amazon warehouse worker.
[1]: https://steveblank.com/2009/12/21/the-elves-leave-middle-ear...
Now you need the job more then the job needs you; eventually you may find yourself in a position where employers compete to have you in the team instead.
As noted in other comments, this DID check for causation and found employee happiness led the benefits, not the other way around.
Article: "However, the authors cite studies of changes within individual firms and organisations which seem to show that improvements in employee morale precede gains in productivity, rather than the other way round."
A theory could be that employers see the improvement in productivity before they are measureble by the methods employed and therefore are happier. E.g. bad processes are replaced which gives happier employees before the gains are evident.
That's the theory - but I don't see the distinction you listed ever proven. People do it because it's the easiest thing, that doesn't make it the best thing. I can just as easily theorycraft that happy employees improve production ACROSS THE BOARD, with lasting and compounding results. The studies that argue this never make the distinction you've listed.
Pressuring a bit on the suckers that got to cling to their jobs still looks like a good short-term policy, especially if the higher-up executing it is also not very happy but is clinging to the job.
That is, the best org is where everyone is level 4 or 5 on the "Tribal leadership" scale [1], but a lot of orgs are at level 2 at the lowest rungs.
[1]: https://emergentbydesign.com/2012/06/28/a-step-by-step-guide...
The reverse where employees feel restricted is bad for both productivity and morale. While procedures have their place (more consistentcy) they also have costs. That sort of strategy may actually work in some cases or be neccessary but it often caps or bottlenecks growth both individually and institutionally. For example medicine is a conservative field partially because of the complexity of the body and the stakes. For every "germ theory" introduction of experimental ideas there are thousands of "just try high doses of amphetamines or radium to strengthen the heart"!
In every industry, there are employees whose influence on the company success is outsized, and who are hard to hire or train. In software industry, they are experienced engineers and product managers. In a fashionable restaurant, they are experienced cooks. In an airforce, they are experienced pilots and repairmen. Etc.
When these people are happy with their work, they achieve great results. When they are unhappy, they look for ways to conveniently jump ship, because they have a number of opportunities elsewhere waiting for them to become available. They are in short supply. Every boss has an incentive to keep these people content and loyal.
OTOH every industry has positions for which supply is plentiful, compared to demand. Aspiring game developers without experience, dish washers, burger flippers, etc, can be readily hired, paid little, and easily fired, too. There is no incentive for their bosses to walk an extra mile to keep them happ, especially when pressing them a bit more yields an extra bit of performance, so they mostly aren't happy about their jobs.