The light/vision/stealth/darkness/invisibility interactions certainly could be better explained...I think that's a valid concern. BUT I do think 5e, particularly the DMG, could be MUCH better organized and explained.
The system isn't THAT complicated but you wouldn't know it by the way the DMG is organized! If you don't know what you're looking for, good luck finding it!
Better organization, better examples of the play loop and overall better presentation in the DMG would essentially simply the game by showing it's not as complicated as it appears.