I’ve been poking around for similar instances to the Salon des Refusés (1863) in the history of art since then to today, where a breakaway group of avant garde artists does their own thing (in opposition to a conventional/traditional academy, established school, or similar), and then eventually works by the members of that group become recognized as masterpieces in their own right.
It turns out the rise of the Impressionists some nine years later in another independent exhibit, and series of subsequent exhibits, meets these same basic criteria. Unsurprisingly, these exhibitions were also met with their fair share of ridicule, as quoted from the Worldhistory.org article linked above:
People had laughed and made fun of many of the paintings. Some visitors were visibly angry at this art they could not or would not understand. There was even a danger of some canvases being physically attacked, as one artist noted in a letter to Dr. Paul Gachet, who had bought several of the works on display: “I’m standing guard over your Cézanne, but I can’t guarantee anything; I’m afraid it will be returned to you in shreds” (Bouruet Aubertot, 189). […]
Most critics found fault with the obvious brushwork of the artists, taking this as a sign of hurried and unfinished work. They disliked the lack of draughtsmanship and vague forms. The use of certain colours was highly unconventional, and the choice of subjects seemed bizarre. Some of the more extreme reactions from critics in the press included: “wallpaper in its early stages is much more finished than that” (Roe, 129) and “…these are paint scrapings from a palette spread evenly over a dirty canvas. There’s neither head nor tail, top nor bottom, back nor front” (Bouruet Aubertot, 189).
Most significant of the critics was Louis Leroy, since it was he who, after being left decidedly unimpressed by a Monet painting titled Impression, Sunrise – a view of Le Havre’s industrial harbour with a fierce orange sun reflected in purple waters – had labelled all of this perplexing exhibition’s art as ‘impressionism’. For Leroy, this was a derogatory term. Another significant critic was Albert Wolff of Le Figaro, who singled out Pissarro for particular criticism, stating that “in no country on earth will you find the things he paints” (Bouruet Aubertot, 216). […]
Wolff was there again to leave his acid comments: “a ruthless spectacle is offered…five or six lunatics…among them a woman…a group of unfortunate creatures stricken with the mania of ambition…” (Howard, 84). […]
Still, some harsh words were written about the exhibition such as “children entertaining themselves with paper and paints do better” (Roe, 179). […]
Those quote cover the emergent group’s first three exhibitions at least, but I intend to keep dredging for other similar quotes showing those moments in art history when the critics and the naysayers were undeniably proven to have gotten it completely utterly wrong.