"Beginner" Anything, IMO refers to any mass marketed, simplistic designed product where there are also more expensive, more focused as well as different feature sets. In just about every hobby, theres usually a product or 2 that beginners are recommended or buy before knowing there are fancier versions out there, usually aided by massive advertising/store placement.
So, with that idea: ENO's are at most outdoors shops, as well as other brands in state parks (locally at least). They have a simple, no frills design that is appealing to both everyday non campers and people like us. TBH, they simply work for everyone.
Absolutely nothing wrong with it being considered a "beginner" hammock, it is just what it is.