I am a part of a couple small online communities with self promotion guidelines/rules that soft-limit the amount of content that you can post as links to your own blog/content. I see this chiefly in smaller reddit communities, hacker news, and tildes.net. It is seen as bad etiquette and you will be softly chided if you are seen to be posting primarily self-produced content and not interacting with the community on the site itself.
POSSE, for those who are not familiar with the term, stands for Publish on you Own Site, Syndicate Elsewhere; or in other words, put your thoughts in a blog that you own and post links to that blog on sites like reddit, tildes, hacker news, bluesky, etc.
There are several advantages to this, if you want to share thoughts that you have on a topic on several different sites, you don't need to copy paste or rewrite your thoughts in multiple times. It also adds permanence to what you are writing. You control the platform that the content resides on, meaning that your content is not governed by the whims on the moderators of the platform on which you are posting. You are able to more easily content that you have written in the past; this is increasingly helpful the more sites you are active on. You are also able to dictate the format and aesthetics the post in more creative ways.
Every community that I have listed so far allows users the option to make a text only post natively on the website. This offers other users of the site a consistent experience when reading and interacting with posts. When you are crafting a post natively on a site, you are much more likely to take into account the culture and community of a site (some communities are stricter about tw's, some userbases are more or less technologically adept, etc). This also leads into being able to craft multiple personas across different sites. The activation energy to interact with a native post, I know I personally am more hesitant to follow a link vs expand a text post directly on the front page.
As is almost always is the case, it depends! I do think that there is a bit of a bias against linking out to a blog/website that is not totally warranted. The reaction of communities for linking something that would be equally worthwhile as a text post is often fairly heavily judged by how much interaction the poster has in the comments after the post is made. I get why this happens, it feels like self-promotion without contributing to the community, but I also think that if the same post was made without comments natively there would be less pushback (note this is only for personal blogs, corporate or monetized blogs deserve pushback without community engagement). Obviously the gold standard is to both make top level content and interact with the community where they are.
I think that blog content should be as platform agnostic as possible, since meta posts about a platform are inherently local and should happen natively on said platform.
I really like the ability to separate the content that you are posting from a platform. Since the debacle that was Twitter, I think that owning your own content has become more attractive. Owning how it is displayed gives a level of creativity that is often not afforded by sites that only allow for simple markdown. I also am finding myself in a mindset recently that yearns for more personal blogs and decentralization of content that is syndicated and found through aggregator communities like tildes and reddit.