No, they are just people that have allowed others to tell them what they like. Shakespeare? Right we all lived in that era so we know that the gibberish is a knowledge and understanding of art. Was he good for his time... no doubt, was he great? Did what he wrote translate well and become understandable to all? Not that I can see, however, it does make a person feel superior when they stand in a room pretending to understand art. Shakespeare got his reputation for being different and hard to understand. Literature professors are solely responsible for it's continued exposure. Is it a good example of the times it was produced in? Of course it is. If produced for the first time now, how would it be judged? Art is two things. It is something to be enjoyed and appreciated. If you enjoy it and appreciate it, it is art. Not just some snobs that think they know what they actually do not. It is all bull including the Andre' vs. Dom Perignon. The only way it is really judged is by how much it costs. Even if a refined pallet is a reality, it is still an individual pallet and what one human being experiences via the pallet may be miles different then others. One persons Dom Perignon is another persons swill. It is a implanted opinion based on multiple elements and not necessarily fact.
To slightly alter your final statement... all opinions are not equally credible and the people that believe they know better will overwhelmingly disagree.