It is not the most important aspect of 1911 accuracy by far but you're not going to get match grade with sloppy frame to slide. The slide stop pin mounts in the frame. The barrel link connects it and the lower lugs. Lower lugs ride on the pin, drivng the barrel into the slide lugs. If you have loose slide to frame the barrel has more latitude to obtain a different relationship with the slide in lock-up.
More important to accuracy is the bushing foremost, lower lugs, and barrel hood to slide. And a shootable trigger of course.