You're right. But this feature is also completely out-of-scope for the type of reader I'm making. Maybe one day, if I'm sitting on a pile of money and have more time than I know what to do with, I may enter into the aggregation aggregation business, but it doesn't sound fun. I think a very small percentage of users want aggregation aggregation, whereas most folks are looking to keep up to date with an ever increasing number of writers.