Comparing the number of main bearings between an I6 and a V8 doesn't work - the I6's crank is much longer, and therefore needs more support. However, it is a decent point of comparison between two I6 engines, and there is a reason that when the L22 was designed in the early 60s, it had a much larger number of main bearings than the two engine designes that came before (Chevy 216/235/etc. and GMC 228/248/etc.).
