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.
At the company I work for we make a website for gaming. 80% of the millions of people who visit it are using a phone, 10% use a laptop, and about 8% use a 4K screen with the browser window maximised. The rest use a whole bunch of things like tablets, desktops with unmaximized windows, televisions, etc. We have text content like blogs, promotions, help pages, legal stuff. It all has to work everywhere. There is no way I would ever let us deliver a layout that doesn't respond to the user's device capabilities. That would suck.
I'm just saying that you have to do the basics right for the "commoner" but it is not necesseraly needed for the "good stuff".
Look at books layout, there are very clear difference depending on target demographics. If you want to mass market stuff, go ahead, do "mobile first" or whatever. But if you have high-quality content that require a good layout, it is not worth much to spend time "optimizing" for access patterns that woud barely get used.
The best cookbooks I have are all physical, because reproducing the experience/layout for mobile is impossible, if you want to do a quality product, at some point you have to define a minimum viable standard, otherwise you end up with with infinite scroll and that's not terribly usefull.