Just wondering why OHC with roller followers need lubrication, if it's rolling contact everywhere? In theory, if we remove the valve guides from the equation, does an engine with OHC roller followers even need to have the top lubricated?

A 1902 Oldsmobile has a roller cam that is outside any engine covers. It is in the mud and the blood and the beer so to speak. It obviously has no lube. It peaks out at less than 1000rpm and has a very gentle cam profile, to the point that you can easily compress the valve(ball valve) springs with yourbare hands.

Even if the followers survived with no oil (which they won't as Rod points out, everything Rod says, plus cam bearings will fail.  

Sure, from experience it is not good practice to run the roller cam followers outside the cover. I could've told you that myself - but why? What is the cause behind it?

If there is no need for lubrication on a so called frictionless bearing, then why do they fail if they are not lubricated?  
There should then be no reason to pack wheel bearings with grease etc.
As a youngster I ran a 2 cycle gasoline engine without lubricating the bottem end, ie the crankcase, the piston had enough oil the way I was introducing the fuel, the big end with the needle bearings gave way.
The end answer is there is always friction, if not you could spin a perfectly balanced shaft with rollers and it should perform like its in orbit around the earth, with zero friction losses. Well I guess we need to get away from gravity too. In the end all friction less metal bearings need lubrication. I suppose ceramic do as well.

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