It's true that, given the options available today, the two usually go hand-in-hand (wider color gamut and HDR). However, one of the arguments Steve makes is that a majority of content (and a vast majority of the pixels in that content) doesn't use colors outside Rec. 1886's gamut. Illuminated objects (natural or manmade) almost never go outside that, so you're usually only talking about a few pixels from intensely-saturated light sources in the shot (like LEDs) that might use those colors. Even then, not a lot of filmmakers feel the need to go there, so their movies will look the same in narrow and wide gamuts.
I don't think the video is arguing against wider gamut or even higher dynamic range as options; modern displays are more capable than older ones, so we need tools to allow content creators to use that capability if they desire. The problem is that all of these things (color space, bit depth, transfer function, absolute luminance values, etc) have been lumped together under one label, "HDR", and some of the implementation details are actually worse than what we had with SDR. If you skip to the "Checklist Recap" portion of the video, you'll see that there are actually quite a few downsides to HDR in its current form, but since most of the standards are tightly coupled, we're kind of stuck unless we move to something better.
I also personally choose HDR versions when watching movies, but that's because UHD content is usually also HDR. What I really want is the higher resolution. I've never felt like I'd be missing out if it didn't have HDR because I've compared the two a lot - they're really mostly the same for the movies I watch with a properly calibrated screen. To each their own :)
