I haven't played Beyond All Reason but looking at the system requirements I'm not surprised it is more fulfilling. 0 A.D. runs on a potato if you look at it threateningly, which makes it a good option to have on a throwaway machine for kids or somesuch.

Those are lowball system requirements too.

You can easily play or spectate a low-unit count game of BAR on any decent 2010+ quad core.

Such a computer won't allow you to play 8v8 that goes into the late-game stage. Sometimes not even 4v4 or 2v2 with players scaling to high unit counts. Some players try anyway. Ignoring player disconnections, half the drama of large-scale games is the one player who's lagging because they're on a potato computer. If the sim doesn't lag, the game will at least be down to single-digit fps.

That means you can't really play multiplayer comfortably, at least not beyond 2-4 players.

For that, you need a recent ryzen or intel. I'd estimate recent as post-covid.

I don't know what combination of things is important; there's larger cpu caches, faster sustained CPU frequencies (TDP and cooling matter there), hardware mitigations for speculative execution bugs, faster ram, resizeable BAR support... but in my experience going from a 6-core skylake-era cpu to a ryzen 9xxx, with the same gpu, made a massive difference. I saw no massive improvement going from a 4-core 2010-era cpu to a 6-core skylake-era cpu; I'd classify both as potatoes for BAR purposes.

My experience is the opposite: 0ad will lag on my laptop once thing become big. BAR will warn that it’s not compatible with my low end intel integrated potato gpu, but it works just fine..