I'm tempted to agree with you, but at the same time, I think the appropriate value for a sensible DPI depends on screen size. Because smaller screens are typically held closer to the user, it's kinda fair to say a 4k TV and a 4k phone screen have the same resolution, in the sense that if both are at a distance so the screen takes a reasonable fraction of your vision, they will have the same level of visible detail. Within a device category that may be less true, but between categories resolution seems like a reasonable measure.