It is not clear to me how "dirt" would not become re-suspended in the oil every time the engine starts up. If the "dirt" does settle in the pan, it is also not clear to me how it would be dislodged when the oil is drained. However, to each his own.
I would suggest that you have a look at this 2004 report by the Alliance of Automobile Manufacturers. Although the report is applicable to modern engines, sludge build-up should be worse for older engines without positive crankcase ventilation systems.
Impact of Low Quality Oils on Engine Wear and Sludge Deposits
