Just my best thought of why it may make a difference to have the plugs or not. The flow area of a .040" hole is .00125 sq in. The flow area of a .005" gap across a 1" long bowed up plate area is .005 sq in... so any plate bowing or lack of flatness can add up fast in that area. And I can see guys getting burrs and grit in there, or leaving out a bolt like a top bolt to oil the chain like came on some SBM's and the plate has a pretty god gap and let's out oil. I'd bet YR is pretty meticulous on his assembly and so is likely to not have such issues.
It is just not a guaranteed oil pressure seal area. So it may be fine on one engine and a crap seal on another that has plate issues or is done in a way that can leak without realizing it. And a weaker oil pump will show pressure losses a lot more readily with any leaks whatsoever. So a lot of variables as to why it may become an issue.... or not.
YouTube channel? That would be interesting....!
