My understanding is that MW is a far bigger factor than throat wear in accuracy reduction (that assumes the barrel was accurate to start with, a good MW reading does not guarantee accuracy).
On the other hand a bad one ensures poor accuracy.
You can have the muzzle cut and re-crowned or tapered back and restore MW as long as the rifling is not worn out which is a result of 4-8000 round through it.
Obviously throat erosion at some point will factor in but usually its a rare case of that before MW.
Shooting hand loads of as low a velocity as you can maintain your desired accuracy with (and above the minimum powder loads) adds a lot of life to a barrel.