I mean, I was playing skyrim at (unmodded) max settings with a gen 1 i7 and 2x HD 7870s. (Not that the crossfire actually did anything for skyrim, so you can consider it a single 7870)
Now, that said, some games ARE CPU bound, World of Warcraft being the classic example. That said, most games that are genuinely CPU bound are typically pretty old, and even though they're CPU bound there's an 'effective limit' on how much effect a good CPU can get you, and most midrange CPUs will get you there.
As for Fallout 4, I have zero idea. I despise what the fallout series has become and do not play it. From what it looks like though, this person seems to find it A-OK.