I never took lapping scope rings too seriously, you know, that's for the hard core paper punchers. But then I had an opportunity to get a lapping kit and the first rings I lapped were an eye opener.
It was AMAZING how little contact my scope rings were making with the scope tube. When you lap, you remove the finish inside the rings so you can immediately see where the "high" spots are. Not only does lapping remove the high spots, but also any machining imperfections, pinch points and slight mis-alignment.
Your rings marry the scope to the rifle making it one unit. One without the other is not much good. One half of the equation in top notch shape and the other only so-so will only give so-so performance. They have to be bound together as a single unit. The rings are the "glue" that binds them (scope and rifle) together causing them to work together as one.
I have become 100% convinced that without lapping, with your rings only making semi-contact with the scope, that there is NO WAY you can realize the full potential of your rifle/scope combination as far as accuracy is concerned.
Further, I believe that it is a simple matter for a minor bump or even recoil to shift point of impact without lapping.
Lapping puts the rings in contact with the scope rather than a small portion of the rings in contact with the scope, which necessitates really torqueing down the rings to maintain your zero integrity, if that is even possible with just a tiny amount of the rings in contact with the tube. Further, it puts tremendous force on very small areas of the scope tube.
Not terribly expensive and quite inexpensive when used with several rifles and considering cost of rifles and scopes. Here's a kit including torque driver for both 30mm and 1" tubes:
Wheeler Engineering Scope Mounting Combo Kit 1" and 30mm - MidwayUSA
This is just a cheapy kit but servicable.
I believe, at the very least, lapping removes one variable that can effect accuracy when chasing after the best from your rifle/scope combo.