Not sure what to tell you, I play on a Mac M3 laptop, best wow machine I have ever played on. Silent, runs at 144 FPS on an external screen with everything on, and I get few if any crashes, which I can really blame on anything other than my internet.
I suspect it will become more and more difficult to get support on the old Intel Macs. I don’t know if you have reasons to keep you old Intel Mac, but honestly the cheapest Mac Mini (no upgrades) will likely run faster and better, and could even be cheaper in the long run due to much lower power costs. Just be careful of upgrades, as while nothing can beat a Mac at the entry level price point, this all changes a lot as you start down that upgrade path, and honestly, unless your doing crazy things, the base model is likely enough.