I think the media comparisons kind of weaken they survey, given that for example most of the MCU/Star Wars plays at the very safe end of PG13, rather than up at the other end. And relatively few games have as much sex as GoT, but frankly few D&D games don't have as much violence, it's just some people are fooling themselves about it or glossing over what is actually horrific violence - that's part of why this discussion comes out of BG3 - you can't entirely gloss over the violence because you see it being committed - see the blood, see the charred corpses, hear the screams, and so on.
If you said, say Heat (the Michael Mann movie) for your R example, I bet you'd have seen like 20-30% more votes on R. Because a lot of D&D games are kind of like Heat but with more jokes, frankly.
Also re: PG13, yes the safest MCU movie possible is PG13, but so is The Dark Knight (!!!), Dunkirk, Mission Impossible: Fallout, Hotel Rwanda, Kong: Skull Island and a bunch of other stuff that's more horrifying than a significant percentage of R-rated movies.
(As an aside, some of the MCU movies I'm pretty sure they intentionally added a minor swear or slightly more violent scene or two just to make sure they didn't get PG instead of PG13 because that would be embarrassing to them.)