When a person hits that subscribe button they are saying, I want this person's content... not I want you @Youtube to decide what portion of content I get.... C'mon guys, to subscribe is an action, which means that sub is saying, give me this content
pic.twitter.com/ie8N97VQzF
But what you're answering isn't what op said. I didn't read anything about notifications in that tweet. What we want are ALL the videos of channels were subbed to. What we get is NOT all the videos (deny all you want, this IS the reality; YT sub feed has for yrs been very broken)