I have always interpreted bones/ghosts as using previous runs as an additional source of level-generation data, rather than a progression mechanic. In the game, it is realistic that other adventurers would have attempted what you are attempting (and died trying). The game could fill in this assumption by randomly generating ghosts and loot, but real-world data is more interesting and nuanced. For example, one of my favorite components of the nethack bones system is seeing the cause of death of the ghosts I run into. Again, 'cause of death' could be reproduced with some random generation, but it wouldn't be as good.

Anyway, I only play nethack on public servers or using the nethack hearse tool, so I don't 'progress' by using my own bones files. Maybe if you play purely locally, you can view your own bones files as a form of progression.