A lot of works that were under-appreciated during their time had their extemporaneous advocates and promoters that had their own motivations that often had little to do with appreciation for the work.
If Kafka's editor had listened to Kafka and burned his works instead of making sure they got on as many bookshelves as possible, or if Van Gogh didn't have the close relationship he had with his art-dealer brother, we almost certainly wouldn't remember their works today.
I don't doubt their are many unknown masters ahead of their time that will forever remain in obscurity.