Aspiring Lurker (He/Him)
It's not an unreasonable presumption, though. There are things it's worth talking with the DM about before they come up, if they're weird or complicated or controversial, especially if you're expecting them to be central to how your character works.One thing I have to get out the habit of doing is: I shouldn't assume a game is "RAW unless otherwise specified." That's just A way to play, after all.
Of course RAW can't cover everything, which is why we have dm's in the first place, even when we intend to use RAW as much as possible.
If a game is playing under that assumption, then RAW matters until... otherwise specified. But if that isn't the working assumption, RAW doesn't matter at all.