I definitely agree with you on critics. It seems to me that critics, like all humans, have their likes and dislikes, but too often they set themselves up as the beginning and end of the discussion about what is "good" art, when the reality is they're just expressing their opinions as facts. Whereas I feel everyone should make up their own minds about what art is to them, and what they like or don't like.

But I don't really agree with you on art historians. My experience with those who look at the history of an artistic medium is they tend to think everything is interesting and worth looking at, but in most settings where one might have contact with an art historian, they're under pressure to whittle it down into digestible chunks for whoever they're talking to (be it students, visitors at a museum/gallery, etc) - so of course they have to focus on the artworks that had the greatest impact on their surrounding culture and audience. There is, of course, an element of personal taste involved, because no human can be 100% objective, but there are some objective elements: the first piece in a completely new style or medium, which inspired others, is often more influential than the millionth piece in that style or medium.