Gatekeepers are important; like or dislike them they do work.
Do you mean like literary agents? Because almost no epic fantasy author was signed up through the normal agent submissions process. For example: George R R Martin, Robert Jordan, Robin Hobb, Steven Erikson, Joe Abercrombie, Patrick Rothfuss, R Scott Bakker, Scott Lynch, and Brandon Sanderson for starters.
And that's without mentioning Frank Herbert and JK Rowling.
The old system of gatekeepers doesn't work, and hasn't for some time. A lot of what is being read and enjoyed is in spite of them, not because of them.
To my mind the biggest weakness of self-publishing is quality.
True, in that there are no minimum standards to self-publishing. But it's increasingly common for new writers to treat self-publishing as seriously as traditional publishing, with all the quality checks in place.
There are also a number of authors who are/fear being forced out of traditional publishing who are now self-publishing, and that's before we mention their back catalogues.
This is the article - from Ann Swinfen, explaining her move from traditional to self-publishing - that made my decision for me:
Self-Publishing - Why and How - Ann Swinfen
In short - even when agents do spot talent, even when publishing editors get behind them, it's the accountants who now decide whether a project will go forward or not.
And because they remain tied to the decline in book shops and shelf space, they are less interested in debut authors, and reducing their output.
Traditional publishers have an increasingly minor market share and no longer have an essential role to play in the market. That's not me being opinionated - it's what the industry reports I link to from this section keep saying.
2c.