I've found that getting published is difficult primarily because the work isn't good enough yet. Getting a really good short story or novel published is easy.
Agents and editors are more than willing to help new writers who show they can write. Without new writers, agents and publishers would both go broke. But at least 90% of what shows up in the slush pile of agents and editors simply isn't good enough to publish. It isn't remotely good enough. Another five or six percent is almost good enough enough, but isn't quite there. It may lack originality, or be just a little too unpolished. Whatever, it isn't ready.
Getting published and finding an agent isn't hard. It's writing good fiction that's hard. It takes a lot of talent, a lot of skill, and a LOT of practice.
Too many writers expect to get the first thing they write published. Now, some writers do start off hot, and publish the first thing they write. But expecting to publish the first novel you write is like expecting to play Carnagie Hall after the first year of playing a violin.
My trouble with self-publishing is that too often a writer thinks he isn't getting published because editors are idiots, when the truth is the manuscript simply isn't good enough. And a bad novel self-published is still a bad novel. It's usually worse than a typical bad novel because there's no one to edit it.