An oiled foam filter that is not cleaned will be excessively restrictive. Dirt will not get past it because the engine likely won't start if the filter is dirty enough.
Both types of filter are effective. I've used equipment with oiled filters for decades and never had a problem. I've never worn out an engine using any type of filter. One would have to be doing a very great deal of mowing to have an engine wear out due to improper air filtering, be it paper or oiled foam.
Personally, I prefer oiled foam. If it gets dirty, a clean one is only five to ten minutes away. A paper element is a drive to the hardware store. Which for me, can be anywhere from twenty to 120 miles, depending on whether I'm at home or at camp.