You do not need the manual. At all.
Just because they went through the effort to put a bunch of info into a place does not mean you NEED that info to do anything. Similarly, just because it can be useful does not make it required.
Now, stop being pedantic and start trying to think of games where you NEED the manual, hence making it, a "main gameplay aspect".
Way to excuse yourself from handing money to more than problematic people...