My friends and I started playing DnD during COVID. We’re all at least normal intelligence, college educated people (I even work in a job where I regularly research federal regulations, so I’m used to navigating complex rules). Our biggest complaint was how obtuse and difficult to pin down some of the rules in this game are.
Six of us spent a half hour trying to figure out how darkvision works, and the answers we found online didn’t seem to match up with what we were reading in the handbook. You would find something mentioning darkvision, but it wouldn’t explain how it worked. Then somewhere else would say something different about darkvision. It seemed like you needed to go to multiple different sections of the handbook to piece everything together. We encountered multiple instances of this.
Our one friend defended it all saying it’s deliberately obtuse to allow for DM flexibility, but most of us disagree with that approach. The rules should be explicitly stated, and then a caveat added that all rules are flexible if the DM wants them to be. There should not be a debatable way to play the game, as far as official rules are concerned. How you bend the rules is entirely up to you.
While it’s true that 5e places a lot of the work on the DM, I think in that case your group just failed to read the rules properly. Darkvision is one of the more well-defined abilities in the game.
When six newbies struggle to figure it out, then it isn’t well-defined. Or at the very least isn’t well structured to find the definition quickly. I will die on this hill.
I think what you’re actually alluding to is that the books are poorly organized, which is indeed a common complaint. Darkvision is very clearly explained, but the explanation is “treat dim light as bright light and darkness as dim light”. In order to understand what that means mechanically, you then have to go find the section on light levels and obscurement (and then the rules on obscurement require you to read the blinded and invisible conditions). This isn’t necessarily a bad thing and is actually how most TTRPGs handle nested mechanics, but D&D notoriously has a really bad index in the PHB, which means it’s very hard to actually find the nested mechanics you need. Lots of other TTRPGs will give you a page reference or something when they reference rules found in other parts of the book. 5e doesn’t.
