MMOs broke me of reading manuals. I used to read them, all of them. I am a junkie for rules and design — I have read rulebooks for far more pen-and-paper games than I have ever played. I have read ~200 page manuals for 4X games.
I now rely on tutorials. Almost all games come with them. Even games without explicit tutorials have a way to ease you along the learning curve.
MMOs broke me of reading manuals because the manuals were wrong. I do not blame the manual writers. What they wrote was presumably correct when they wrote it. Then two classes were cut in the last month of beta, one was re-done, one changed its name, twelve abilities changed names the week before the game went gold (including several that swapped names), and half the numbers changed. Then everything changed within the first three months, so only the general class descriptions were correct. Then the vision of some classes changed a year or two later. The developers’ online documentation is rarely completely correct, so let us not even hope for the printed version that needed to be finalized a month before the release date. (And people buy printed guides as they would for single-player console games, ha.) Some MMOs learned this and made the manual uselessly vague, which is another non-solution.
Even a decade ago, you went to the fan sites to learn how the game really worked. Now every game has a wiki and multiple forums with new user guides. It has become a measure of how newbie-friendly a game/community is: you need some small number of helpful, literate people to write the guides, so either the game is popular enough to have several of those people (good sign) or a small game has enough concentrated awesomeness in its community to have several (good sign). If a game is worth playing, people will be encouraging you to get started.
Now I get many games via digital distribution. Do they come with manuals? A few games have something on the start menu that directs you there, but I do not know if they included PDFs of the manual. Maybe it is in a folder somewhere? It would be helpful if the Steam library included a “manual” button, but the prominent one is “play.” So I play, rely on the tutorial, and that usually sees me through.