Plenty of things can make a gun inaccurate.
Barrel dimensions inconsistent, bolt face not square, action not square, improperly torqued barrel, improper bedding/pressure points, recoil lugs not square or bedded properly, actions screws improperly torqued, barrel crown imperfections... and probably a bunch more, that's just off the top of my head.
No, there's a lot more to it than the shooter and ammo.
Still happily answering to the call-sign Peetza.
You do not HAVE a soul. You ARE a soul. You HAVE a body.
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.