165th,
I posed this question when I was restoring my HO engine. The answer is
NO. NJSteve weighed in on this issue when I mention here that I had replaced the original stamped steel rockers with roller tip rockers from Comp Cam. Fortunately, Steve told me I was fixing to hear a big clatter under the valve covers when i fired that Jessie up. Boy, was I glad he was on the forum that night. He jokingly said....guess how I know. Anyway the conversation went on to explain that Pontiac used the bolt on baffles/ drippers to ensure good oiling on their engines when they encountered long periods idling in slow bumper to bumper traffic. Later they replaced them with the dripper type valve covers and then eventually stopped doing anything after they realized they weren't needed.
I like them. I think they serve a good purpose, however small that may be. I like the fact that it keeps a lot of oil off the valve cover and controls splatter. My engine is none the worse for not running them though. I'm keeping them though for no other reason than they were were part of my original engine.
Some of the the more educated engine builders here may be able to add more light on the subject than me. Hope this helps.
Eddie