They certainly were. Bruce Berndt is one example of a mathematician who has spent an entire career proving the results found in Ramanujan's notebooks. He has wr

They certainly were. Bruce Berndt is one example of a mathematician who has spent an entire career proving the results found in Ramanujan's notebooks. He has written a number of very thick books showing methods of proof for all his results. Notice that Ono says that only a few people knew about this stuff. Another way of saying the same thing (the more usual way in my opinion) is that "this was already known by the experts".