Backpacker magazine exists just to sell advertising and deliver it to readers. Nothing more.
I believe they use the term ultralight as a marketing term, not a real term with real meaning. They know ultralight is better so they coopted the word to refer to stuff that's ordinary weight.
They could never sell real ultralight gear. It's too delicate. It won't hold up to abuse. They love to state that as a praise-worthy thing in their reviews. Holds up to abuse. Why would I want to carry stuff that's heavy and then abuse it when I could carry stuff that's light and take care of it?
So then "fastpacker" is the term they have to use to describe people who are actually ultralight backpackers. They have redefined ultralight to mean 3lb backpacks, 2lb sleeping bags and 5lb tents so people carrying around items with the words "gossamer" in the name have to have some other word like "fastpacker."
Fastpacker is slightly pejorative. It sounds like someone who doesn't take time to smell the roses. It sounds like someone who's really hard core, running the trail for fitness, not enjoying the beauty.
The other word they use is "minimalist". Also pejorative. A minimalist is not enjoying themselves, either. They are denying themselves not just pleasure but in the world of backpacking, they are denying themselves necessities like warmth, food, sleep and adequate shelter.
Minimalists and fastpackers aren't going to buy a lot of gear so they have to define these people as people their target audience doesn't want to become because, as a magazine selling ads, they want people to want to buy more gear, not less.
