Self-promotion isn’t inherently a bad thing. But it’s very shitty when somebody goes to a community and just drops their blog link.
It’s not obvious if one person does it, but once you have more than a few people doing it, the communal pool gets polluted, people get frustrated and they start to leave.
And eventually whatever marketing community you tried to set up ends up becoming filled with nothing but blogspam.
The way out of this, in my opinion, isn’t to ban linking to blogposts altogether. You can’t eliminate self-interest from the equation. If people aren’t allowed to link to their blogposts in one space, they’ll go somewhere else.
The way out is to have community standards where everyone is expected to contribute to the conversation.
I’ve posted links to blogposts to reddit several times, and have had them do quite well. The trick to doing this is to make the blogpost an afterthought, and to focus instead on contributing to the community space. You do this by sharing enough of the content in the community itself. On reddit this means summarizing your blogpost, your findings, etc – so that anybody who doesn’t want to read your blogpost is still able to get some value from the post.
I also recommend leaving comments with questions, and with your personal thoughts, what got you writing the blogpost to begin with, what you grappled with, what you’re uncertain about, what the next steps might be. And engage with people in the comments.