most cannon armed plane have attack mode due to cannons and strafing capability. Not tied to historical use as much as game scoring.
Aircraft with similar (or better) strafing capability to A6M3 that don't have an Attack option:
C.205
109-F4
109-K4
Spit V
Spit IX
Spit XIV
Yak-9U
Doesn't add up.

I think the 109-E4 is also Fighter only.