These statements don't have anything to do with PERFORMANCE claims about Mobil 1. Normally, when someone says something isn't all it's cracked up to be, they mean that it's not as "good" as it's claimed to be. Well, Mobil 1 is PAO-based, so it does meet that claim. And depending on what definition you use for "synthetic," Mobil 1 could lay claim to being the only OTC synthetic out there.
Delvac 1 is also PAO. The 5w40 grade tends not to thin out in the UOAs we have seen posted on this site, whereas Mobil 1 0w40 does have that tendancy. Delvac 1 has no moly, but Mobil 1 does. Some would say that Delvac 1 is a better oil overall than Mobil 1.