I have to disagree with the specifics of that statement, but in general you’re absolutely right.

The key to great percussive sounds are fast envelopes with the “right” shape, and the A4 has plenty of both.

The AR will be able to make some sounds you can’t make on the A4, but then again the A4 can make a whole range of sounds you can’t make on the AR.

However, the main point here is that for a “general purpose” subtractive analogue synth, the A4 is extremely well suited for creating percussive sounds. I don’t think there are many synth of this type out there that can do a beter job at it.