Sentence:  But in conversations with people who listen at speeds higher than 2x, it became clear that many podfasters are above all, <WSD>completists</WSD>. That is, they have an almost obsessive need to listen to every episode of a podcast that they decide to commit to. 
Meaning of the word marked with <WSD> tags:  A collector who strives to obtain a complete collection of some type of thing.