I don't think you can say Adams and Maier were devoid of education/exposure to formal notions about art, Adams moreso than Maier. Maier had talent, and her work deserves recognition. But she didn't produce a game-changing body of work - she was photographing within a well-established genre, and frankly, never sought the publicity she is now receiving. Adams, however, did produce a genre-defining style of work, and if you read his bio on the Wikipedia page, he was in constant contact with other artists who were both his contemporaries and his seniors, through whom he would no doubt have gotten exposure to art history. I think you can certainly say they (Adams and Maier) did not have formal academic instruction in art history, but to claim that they were unaware of it would be erroneous. Grandma Moses was an outlier, a one-off, and her commercial success is not a good argument - she produced work at really the end of a very long movement of American folk art, very much steeped in a tradition. So if anything, you could say she was the MOST indebted to art history of the three examples, although it would be a very specific, narrow art history.
If you want to find examples of artists who broke the mold without having first seen what the mold could provide, these three are not good examples.