I sort of agree with your point but your analogy with Chess is not a good one.
Chess is played with another person. Not that it is possible but reading spoilers and looking at source code is sort of like cracking open the persons brain to figure out what sort of general strategies and tactics they will use on you... it is not equivalent to learning the rules chess.
> reading spoilers and looking at source code is sort of like cracking open the persons brain to figure out what sort of general strategies and tactics they will use on you...
No it isn't. That would be running the game in a debugger so you know what will happen. Learning the rules of nethack just tells you what can happen; this is absolutely the norm for everything else you do.
In fact, there is one such person commenting here! To them, learning what can happen in the game is cheating: https://news.ycombinator.com/item?id=11523094
This makes all the sense, to me, of excoriating people who want to know the rules of chess before starting to play as "cheaters".