There are some writers who are tedious in their complaints. I don't know what causes it exactly. It is a combination of the awful sense of isolation and rejection that writers live with, and the tremendous ego that makes really good writing possible in the first place.
Maybe there are two problems at work here:
1. The writer who can not write. He or she is like the baker who can't bake. Is there a reason to call oneself a baker if you can't make a loaf of bread? This type of person is the artist, and is usually a different breed entirely. I have here a person in mind. He came to live in Ithaca a few years ago. He thought, in a puerile way, that moving would make him create. But creation wasn't his goal; narcissism was; and he degenerated into drug use, booze, a DWI arrest. And what did he get out of it? That life is a work of art. That he is art. And what does he have to show for it? A pointless work of flattery for a band he worships. Like most of his type, he became a critic and a sycophant. In the end, his efforts are a kind of meaningless example. Looks kids no hands.
2. The other type is the writer who has so many theories about him or herself and the process of writing that he or she is hamstrung. Writing should come from the writer like breathing from the lungs. There are snags and points of friction. But writing should flow. It may not always have the quality one wants, but expression is the key. I have a writer in mind here. She creates within certain narrow confines of her opinions. The work is good, but it fails on a deeper level. There is a lack of connection with the work and the world. In the end, that gap is felt by readers, and they don't want to read.
When people tell you, over and over, that your work fails to engage, it is time to search out a new avocation, or take a good look at the motivations for writing.