This was my dad's theory, starting with his first Ford model-a as he was an "Oily" working in the Oklahoma oil fields in the '20's. A life of living and working in the oil fields, including some of the labs, allows one to learn just from trial and error, I guess. Not only did he say to change the filter since it captures the particulates, but also because as it does so it can restrict flow. another thing we did was always change our own oil. Warm up the engine a little, then open the pan and allow to drain for a half-hour or so. Since a lot of the heaverier items, such a metal filings, etc could have time to run out. He always ran his fingers through the capture pan, too, looking to see what was there. We did this with tractors, dozers, anything that used oil. Maybe somethign to it, maybe not but before oil analysis programs, it seemed to make him feel better