What is it about dirt getting into a saw blade (as opposed to, say, sawdust, rock chips, etc (presuming the right blade is being used, of course)) that will kill a saw blade?
I've seen it happen to sawzall-type blades and chainsaws - but don't see what is so "special" about dirt that would cause those issues: especially when the self-same blade can be worked through PVC, pitch-encrusted trees, etc with little-to-no (or "normal") wear/damage.