In my experience, product people who know what they are doing have a huge impact on the success of a company, product, or service. They also point engineering efforts in the right direction, which in turn also motivate engineers.
I saw good product people leaving completely destroy a team, never seen that happen with a good engineer or individual contributor, no matter how great they were.
I have seen firing a great/respected/natural leader engineer result in pretty much the whole engineering team just up and leaving.
I have yet to find a product person that was not involved in the inception of the idea that is actually good (hell, even some founders fail spectacularly here).
Perhaps I'm simply unlucky.
But he was also technical enough to have a pretty good feel for the complexity of tasks, and would sometimes jump in to help figure out some docker configuration issues or whatever problems we were having (mostly devops related) so the devs could focus on working on the application code. We were also a pretty small team, only a few developers, so that was beneficial.
He did such a good job that the business eventually reached out to him and hired him directly. He's now head of two of their product lines (one of them being the product I worked on).
But that's pretty much it. I can't think of any other product people I could say such positive things about.
It's different with engineering managers (or team leads, lead engineers, however you want to call it). When they leave, that's usually a bad sign.
Though also quite often when the engineering leaders leave, I think of it as a canary in the coal mine: they are closer to business, they deal more with business people, so they are the first to realize that "working with these people on these services is pointless, time to jump ship".
Of course, if the product suite is clueless, nobody is going to miss them, usually it's better the have no dedicated product people, than having clueless product people.