If you wonder why there seems to be a big gap of 12-15 years where not a lot of new good SF authors came out in book form, except from Baen, it's because the literary elite decided SF should be about identity politics instead of about science and speculation
Or, it could be because that's what people want this decade. I'm guessing a lot of the serious SF market is spending more time on MMORPGs these days than quietly reading books in the corner, myself. At any rate, there is no gatekeeper any more, it's trivial to self-publish. Some of the big establishment names started out that way and just found it easier to let someone else handle the marketing and organization.