Motives of course can vary, but usually when a company has significant employee turnover it is due to one of two reasons:
- Organizational changes (restructuring, saving costs by reducing workforce, ...)
- Voluntary turnover (people leaving the company)
In both cases, I think it is a good metric for anyone interested in a company, whenever it is to join it, to invest on it, or simply to collaborate with it.
If there were some important restructuring you want to know about it. Did the company had poor management and it changed? Was it because it had to cut costs? or maybe because somebody decided to close a line of products without re-converting employees?
We live in a world where people are often seen as numbers. Even the department in charge of people is called "Human Resources", as if categorized similarly as hardware, transport and other types of resources available to the company. So it often happens that when you need to save money, usually you save some of it by reducing the amount of salaries to pay. I'm not going to dig into if that's always unfair or sometimes justified, just state a fact.
It is also really revealing if you can gather info of employee turnover, specially on the main taskforce. I'll exemplify with a tech company: do engineers, product managers and UX people leave almost every month, or is it instead considered an infrequent event the action of somebody leaving the company? do employees on average stay for many years, or is the rotation high? and if the rotation is high, is it only employees that had been for some time, or also there's a number of new hires that don't last much?
And even more revealing (IMHO at least) could be to weight the seniority of the people leaving vs the senior roles that have been at the company for long. If there's a sudden stampede of senior roles that look relevant for the company, either they are going to build something together, or something smells off. If a place has mostly "fresh" senior roles, what made all that old guard go away?
Again, this might not be bad on itself. Maybe the company was in desperate need of fresh air and change, and the new blood will bring radical new ideas and fix things up. But I think it would always be relevant to know what happened, what triggered that disruption.
It's sad how the internet (exceptions like Wikipedia or Archive.org aside) has evolved into a group of huge, closed "information warehouses". Sure most of them are "free" (we pay with our data), but we can only use it in certain, limited ways imposed to us.