I'm doubtful of whatever sort of nonsense philosophical rationalization Dorsey comes up regarding how he thinks users should use, and should want to use the service. It's likely this:
> And while Dorsey said he’s less interested in maximizing time spent on Twitter and more in maximizing “what people take away from it and what they want to learn from it,” Anderson suggested that Twitter may struggle with that goal since it’s a public company, with a business model based on advertising.
I'm fairly certain that Anderson's expectation here is probably true, and that Dorsey is at best disconnected from the reality of how Twitter's business operates if he's not being outright disingenuous. The number of ads shown increases with the amount of time spent using the service, and assuming there is some business unit within Twitter tasked with increasing revenue, that business unit will likely attempt to increase time spent using the service. Inserting this extra garbage and preventing users from disabling it serves that purpose because it makes it more difficult to tell when you've reached posts you've already read and forces you to scroll longer to reach them.