Presentation of the content is as important as the content itself. I would argue that it is part of the content. It serves to direct attention and highlight the reading path.

Content isn't just blobs of text and media that follow linearly without hierarchy.

Just because you have the technology doesn't mean you should desperately try to use it. One needs to make a choice about how his content will be laid out and how much space it shall require. Considering tablets and laptops are ubiquitous, it is pointless to optimize for narrow mobile consumption unless it is the most trivial content (just a text scroll, basically). And if that is the case, you have no need for fluid typography.