Lost my cam

I'm with you, skizzo. As a private builder my perspective is it's up to me to make sure everything is working together properly before the customer ever gets to influence it. So if it's all done right, the over the counter diesel oils will be fine for most mild camshafts, even those noted as "hi rate of lift" but are of such a size that it doesn't make much of a difference.
In regard to particulates in the crankcase and oiling system... The issue is not just in the system. IMO, once the oil enters the pickup the filtering will take effect and will be as effective as that system will typically be, depending on the filter and oil used. Meaning big hard particles will wear the oil pump faster, and a large amount of junk will clog the filter and cause it to bypass. The secondary issue is spashing oil. Piston skirts and rings are very susceptible to that along with the timing set, and lower valvetrain parts. Iron will wear on iron. It's that simple. So by not taking everything out and cleaning it, and "sanitizing" the system, owners run a risk of creating a very fast rate of wear. Like tens of miles worst-case.
That all being said - when I was younger I took a hydraulic roller cam and ran the lifters with no dog bones (retainers that keep them aligned with the cam lobe). It ate it in a matter of 30 miles, and it put iron of all sizes into the oil system. I then pulled that cam an lifters, put in a new hydraulic flat tappet, broke it is, and drive that engine another 2 years before I blew a piston apart under nitrous abuse. So.. it's a gamble. Only the guy paying for it is risking anything so IMO it's up too him/her.