Whole idea behind ARM was running at full speed of ram. Amiga had very little Ram BW to spare for CPU so ARM2 would be throttled by narrow slow ram bus in the Amiga.
Well, yes, but that is only half the story, so on its own, it does not add up.
The whole idea of ARM2 (that specific version, not ARM1, not ARM3) was that clever use of the RAM bus meant it could run at full DRAM speed.
But the other side of the coin comparing with the Amiga is that the whole idea of the Amiga was that ~5 years earlier, it was possible to do amazing unprecedented general stuff for gaming purposes in sound and video chipsets that no other computer at the time could do...
Leaving the CPU almost irrelevant. Which is in part why The Next Amiga, the Hombre, simply discarded the 68000 altogether and switched to PA-RISC.
Which infuriated the fans even back then because they wanted their backwards compatibility.
The core concept of the Amiga and Hombre is "in 1982, what amazing non-dedicated sound and video can we do in hardware for a mass market price"?
By the time it was a product, this was contaminated with "it's also a general-purpose computer" and "look at us, we have multitasking" and "look, it's a 680x0 machine, but with multimedia!" and "look, it can emulate a Mac!" and "look, it can run Unix!"
Different selling points selling in different directions.
Given the raw computer power of the Archimedes, it didn't need any fancy chipsets. They became irrelevant. Sure, yes, the Amiga could do stereo digital sound and multiple bit plane colour 2D graphics and still have enough power left over from a 7-and-a-bit-MHz 68K to run game logic.
The Archimedes looked at that, and went "how about we just do all that in software?" And bundled a solid shaded 3D demo for free. Never mind the bouncing ball, never mind the Juggler, this you could play.
The Mac was "in 1984, how much Lisa can we keep for how little money?"
The ST was "in 1985, how cheap can we make something that looks and works like a Mac but can do colour and sound, so it can play games?"
The Archimedes was "in 1986, can we do a 32-bit RISC machine so cheap and simple we can compete in the same market with Commodore, Atari and the PC compatibles?"
