[RichardJ]

>>but what does setting the points with a dwell meter vs manually have to do with them becoming corroded and pitted?<<

I didn't say it did.

New point contacts are smooth and shinny. After a few miles they take on a course appearance caused by about 300volts arcing across them when the points open. If you don't understand where the 300 volts comes from, you need to read up on the Kettering Induction Ignition System.
In the first image, the enlarged points show a course, gravelly surface. They show a .016" gauge giving a .021" actual gap. Filing with a small metal file will help provide better results and in the end a more reliable dwell. But, they still won't last as long as new before they need attention.

The real problem with using a feeler gauge is that it requires a delicate touch. The point arm spring is relatively soft and the feeler gauge is a metal pry bar. If you don't take the feeler gauge out of the pack, the gauge pack acts like a pry bar handle, giving even worse results.
If you ask 10 guys to set the gap on your dist and check with a dwell meter, you'll probably find 3 guys that set the gap correctly.

The second image shows misaligned contact points that will go out of adjustment very rapidly. Many guys don't bother to check and the Chinese made points are worse than ever.

A couple guys mentioned the condenser. The easiest way to check to see if the condenser should be replaced is to look at the used points. The condenser should be 0.18 - 0.22 micro farads. In the first image you see metal transferred from one contact point to the other. The job of the condenser is to suck up that 300 volts. If the condenser capacity is too large or too small, metal will be transferred from one point contact to the other.