If you have two planes of exactly the same type, one pitted and one not, for the same price, then buy the un-pitted one. Truthfully, I own both and if you are looking at smoothers then pitted soles at the plane mouth edge could potentially make a small difference in the final surface. Chances are though that you would never notice the difference.
Pitting on any blade can be another matter entirely. Any situation that interferes with having a pristine edge affects the type of finish the blade leaves behind. If the blade is used in a situation where the surface finish really matters then you have to have that pristine edge. Because of the need to have a flat back on chisels you can’t eliminate the pitting on the back without taking material off of the entire back. Plane blades can often be salvaged though by using a back bevel, many times by just using the “ruler trick”
Blades used in any situation where the surface will gone over again, such as when you go back over the surface with a smoothing plane, does not require as pristine an edge on the blade. Likewise, surfaces such as tenon cheeks, drawer bottoms, etc. don’t require the same quality of finished surfaces that more visible surfaces do. Save the super-tuned tools for the work that requires the resulting finish.
Other edged tools such as drawknives can still be used with some pitting if the edge itself can be established to a pristine state or if the user can avoid the pitted area during use. Many a tool has been ground past the point of no return trying to get the perfect edge when the work it was intended for didn’t require it.