The post quoted did indeed nail it IMO.
But I don't think those who pulled the trigger on buying a whole PC in addition to Mac just to game are the audience here: those people clearly value PC gaming a lot, spending that kind of money and going through that much trouble having the necessary setup at home, taking space and time to build and maintain. Those who care that much won't be satisfied with the state of Mac gaming and continue owning those PCs.
It's for those who would like to play on Mac but currently don't play at all on anything because games they'd like to play don't work on the only performance computing device they have - that Mac.
The second category of people I'd like to add are those who were really on a fence between getting a Mac and a PC (probably laptop at this point, as laptops are sufficiently similar for such a fence to be realistic, desktop PC and desktop Mac are very different machines in comparison), could have gone either way, but would prefer a Mac slightly, but also wanted to play games - not enough to own 2 computers, but enough to begrudgingly choose a PC over a Mac just for that reason.
Those folks are likely to buy a Mac instead next time they buy a new computer, which is probably going to be years from now, for some - years from the point in time when gaming on Mac because actually accessible and good, not immediately on spot.