It's complicated. The soul of Nethack is opaque design, secrets, and emergent gameplay from mechanical interactions. In theory, the best way to play Nethack is by going in completely blind ("unspoiled"), so that you maximize the sense of discovery which is its most compelling trait. But in practice, I highly doubt that anyone in human history has ever beaten Nethack without looking up any spoilers. At some point you just get frustrated, decide enough is enough, and look up whatever spoilers are necessary to beat the game. Even getting started is rough for a beginner without spoilers, but at the same time taking a spoiler-maximalist approach is probably going to result in a pretty lackluster experience.

I'd say that, to some degree, roguelike game design has moved on, and when it comes to hilarity and sheer mechanical depth and breadth, games like Caves of Qud are probably better at evoking the feelings of Nethack without being so absolutely reliant on spoilers (which isn't to say that the game isn't still largely opaque, just that the essential parts are better-communicated). And on the flipside, anti-Nethacks like Dungeon Crawl Stone Soup make it a design goal to be fun and playable even assuming a totally spoiled player, by focusing more on tactical and strategic decisions and being forthright about including all necessary information within the game itself.