Again, they are your chains and your saws, and another good reason not to loan them out to others who view them differently!
I don't mind running a chain that has bar oil and some wood chips on it though my saw, because that is the world that they live in. But if I can, I try to avoid tar, sand, etc. in my bar grooves, under the clutch covers, inside the nose sprocket, etc.
I also like to keep that stuff out of my files and grinder wheels. Just my preference.
If MR4WD is cutting up dug out stumps, they are going to be full of sand anyway, so it may not matter in that case.
The chains I was cleaning were salvaged, and I had to clean them to inspect them as well. Found some burrs, a broken tie strap, mis-installed links, etc. that I took care of. If it is your chain and you just have bar oil or pine sap on it from some recent cutting, that, again, is a different story.
Philbert