Fair enough. (Ryzen 5 though? Really?) But I would think, if you're at least a semi-serious gamer, $1,000 isn't going to get you your PC. What I've been able to spec for $1,000 without monitor, keyboard and mouse will not perform as well as the specs I'm on my new iMac. So why spend the money then on a separate gaming machine?
I would say a reasonable machine that will perform at least as well as the new iMac (at least mine) starts at about $1,500. But that's still not out of this world, and I think the point you're making is that if you like Macs, and can get away with the base model, and you like to game, then buy both. And I agree. You can always upgrade the PC for gaming, not so the former. However, if I'm buying the i7 with the 5700XT and I like to game a bit, then I'm fine for a good while.
Long term, if I really like to game, a separate PC makes sense from the upgrade perspective, so spend the money. But I think unless you want a decent rig, and you've already got a decent Mac, then I think a PC gaming machine is a waste of money. Certainly if you tend to upgrade your Mac every 3 years or so.