I think one of the problems is that Substack has as much editorial oversight as a personal blog. Despite that we treat its contents as articles instead of opinion pieces that see no fact checking beyond what we in the commons bring up in separate forums.
I would have used the word 'article' for any post in this format and I don't view that as giving it an elevated status. I didn't even notice it was Substack and certainly don't view Substack as any different than WordPress or Medium for reliability.
It's an article of writing the way that a shirt is an article of clothing.
