Google's John Mueller said at the 3:16 mark into a webmaster hangout from December 13, 2019 that Google does try to understand the blog comments section of a page but at the same time would still categorize that section as primary content.
We have covered many times how Google reacts to comments sections over the years and we've heard Google said they can help or hurt your site. But it is interesting to hear that Google considers comments as part of the primary content, unlike navigation, footer, etc but at the same time does try to understand that you do have a comments section that your staff did not actively write.
John said in the video answer "We would try to understand that these are blog comments. But essentially the these are a part of the the primary page."
The question was:
Does Google consider blog comment as main content or supplemental content?
John Mueller responded:
It depends. I mean we see it as a part of the page. So that's something where we would probably see it as part of the main content. In the sense that when we look at a web page we we have things like the navigation all around, the footer, the sidebars, these things which are kind of the parts that we would see as boilerplate content, so not as critical. But the the blog post and kind of the the changing content on a blog page which would include the comments, is something that we would see as a primary content.We would try to understand that these are blog comments. But essentially the these are a part of the the primary page. And sometimes what can happen is that maybe you don't have a lot of content in your blog post but there are lots of really good comments on there. So it's important for us to say well this could be something that is really useful for this particular page, so we should not ignore it by default.
Here is the video embed:
Forum discussion at YouTube Community.