Google rich snippet (star rating) for regular articles?

I'm not sure if I'm using the right terminology, but I'm talking about when a blog post has a spot for users to rate the post, 1-5 stars, at the bottom.

Then, sometimes in Google search results, you'll see that star rating which grabs attention and presumably gets clicks.

However, 1-2 years ago, I read Google is no longer allowing that rich snippet to be used in that way, and it's meant for things like book reviews, software reviews, etc.

Yet I just saw a competitor's how-to article with a rating based on user votes, so evidently it's still being allowed by Google.

Anyone know more on this?