I'm not sure RSS readers are supposed to solve your issue. They are readers — they allow you to read stuff you subscribed to.
Discovering stuff you want to subscribe to is an entirely different task. Idk, try searching blogs or sites that interest you or ask others what they follow.
If my RSS app would "suggest" me articles not from my feed I would uninstall it immediately.
Inoreader might have something like that, probably that's why I stopped using it.