Sean Dyche and Tony Pulis are brilliant with low budget, hard to beat teams but are probably not suited to teams that are expected to win most games.
If they were promoted above this, it would be in essence the same job but really it's a different role, requiring different skills.
I think this is what occurred to Moyes although I think he had earned the right to manage at a higher level.
Being a football manager requires quite a broad range of specific skills such as communication, psychology, coaching, tactics, identifying talent, managing a budget, managing a team of coaches and other analysts, medical knowledge.
It takes time to develop these skills. Footballers live in a bubble and although knowledgeable, still have a lot to learn about management.
I don't think it's a coincidence that so many top level managers actually never played at a high level.