Earlier quoted context omitted.
To any non-tech person, "high DPI" is probably more likely to cause confusion and is just as variable in definition. To (almost) any tech person, "retina" is common enough that everyone knows what you're talking about. Being trademarked doesn't really affect the meaning of a word once it's part of popular parlance - Kleenex, Band-Aid, Hoover, Google...
I disagree but I got down voted enough to guess people like the term???? It makes zero seance. Your retina is the part of the eye that converts light into signals for the brain. Your screen is a display and has nothing to do with converting signals.
It makes sense in the detail that it matches resolution. Our retina is the fundamental limit to our visual resolution. Like the pixels on the screen. Would it make more sense to call it a 'retina-matching monitor' instead?