Here are my accumulated experiences from many years of both attending and organizing small and large conferences.
Conferences have not changed their basic formats much in the last 30 years. They are still mostly about one-way communication: a speaker (too often a white male) telling you his company’s views on things, accompanied by Powerpoint slides. Your role in the audience is to sit still and hope that the speaker will tell you something you don’t know already.
These types of events are inefficient if the goal is to communicate, inspire and create real learning. This format is also increasingly out of synch with all the other evolving forms of media in the internet age, where it is about two-way communication and the users are active participants in creating experiences together with each other and the publishers.