no games are good using mac mini, buy a suitable gaming pc
This just
flat out isn't true.
Do you get value for money from a Mac if your primary goal is a gaming PC?
No.
Can a Mac (+eGPU) play current AAA games?
Yes. And generally speaking, they play very well (GPU dependent).
As I mentioned 'Control' above, I'll mention it again. This is a game that even the Xbox One and PS5 struggle with; my Mac mini + RX 5700 XT played it at a consistent 60FPS on the highest graphics settings (sans ray tracing, but hopefully when Big Navi is out that'll be resolved).
I just started playing 'Star Wars Jedi: Fallen Order', I've played through the first mission with the highest graphics settings (iirc) and also get a consistent 60FPS.
On the other hand, is a Mac mini + eGPU going to get you a perfect setup?
No. I tried to play 'Call of Duty Warzone', and I was facing some janky graphics.
So out of these three AAA games released last year running on Windows 10 under Bootcamp, two of them were flawless. The third I suspect is some poor support from the developer regarding AMD (e)GPUs (requires more investigating).
Separately, I've also had no issues under macOS running Cities: Skylines, or playing older AAA games in Windows such as GTA 5, Portal 2, etc.
If your primary goal is a gaming PC, then sure, a Windows-based setup is most likely the way to go. If you need a Mac and you don't want two PCs, then an eGPU is not a half bad choice.*
* Discounting any ****** OS issues (no FileVault, boot logo, startup manager, etc) issues you may face.