I'm in the same boat, inside any given org I can tangibly feel that "jack of all trades" is in huge demand... and I find myself working long hours due to internal demand for this role inside companies.
Like you, in my 20 years doing this type of role (wearing a large variety of different title hats) I've never been HIRED to the role. This feels odd, given playing the role always keeps me in high demand internally to organizations.... so if its something organizations crave internally, why don't they hire for it?
When eng/prod/ux "broke up" and became separate job roles in the post-Google and post-MS world, I found it /very/ frustrating, because I'd rather straddle all of these objectives. Additionally, I find many companies fail around these seams, because its hard to pragmatically find the optimal solution in the broad eng/prod/ux tradeoff space when you have the "deep knowledge trees" spread across many heads, with the limited bandwidth that entails.
When I started taking senior eng management positions, I naturally thought I would change this, and explicitly hire some "jack of all trades" folks. I was surprised by how hard this is to do, harder even (for me) to evaluate than specialist knowledge, was distinguishing pragmatic and effective "jack of all trades" types from, well, bullshitters. This is funny, because the really effective "jack of all trades" I've observed are in many ways the farthest from BSers possible, they're usually so broadly knowledgable partly because they are so voraciously pragmatic that they end up learning a lot of different things. But from the outside, I wasn't personally successful in confidently distinguishing people in an interview context.
The problem is there's a similar appearing archetype to "jack of all trades" the "always reading never doing" person. Conversationally, they can appear similar. And I found (and find myself) that its hard to test jacks-of-all-trades because they often don't keep knowledge at their fingertips, part of their skill is fast learning. But even if they spent serious time using a technology, they still need 4 hrs of work in it to look surface competent again (I think because they're constantly swapping knowledge in and out, vs a deep knowledge person who have practiced the same patterns over and over and over).
So my limited experience as a "jack of all trader" was:
1. Yes, companies seem to get a LOT of benefit from really good people with broad skillsets.
2. But I personally don't know how to select the good ones in hiring. I suspect other people have found good ways, I'd be curious to hear about them :-)