Think of it as a mini-html site that follows a specific set of visual JS and CSS protocols so that consumers have guarantee of its behavior (will not have crazy ads, gifs or third party content) and behaves consistently.
Kind of interesting avenue for publishing content on the web that isn’t tied to any specific platform.
I’d even go further and say the web needs more of these kind of things. All websites behave differently. Maybe we need a visual protocol also for general web apps (just like this web stories) so that we have consistent behavior. I dare to call this protocol Web Apps.