Thankfully for things other than books (and maybe also for books), a lot of companies offer two day shipping now. Sometimes there's an order minimum for that but I find that most of the time my purchase exceeds the order minimum anyway.
Both KDE and Gnome can be seen as pretty bloated. They come pre-packaged with a lot of programs and tools that sit around unused, possibly even having corresponding daemons running for no reason.
For someone who doesn't want to think about their computer, and just want to know it's prepared for anything, they may want that. But if they left windows/mac to have a smaller, simpler OS that isn't wasting CPU cycles or disk space on superfluous stuff, then KDE/Gnome might not suit them.
Edit: that said, I've heard of a lot of alternative DEs/WMs, but I've never heard of JWM. I've heard good things about Budgie, might also check that out.
They're using a window manager over a full DE, so it's likely the usual case of preferring minimalism to the very complete desktop environment (which many consider bloated). I'm a window manager person myself, but I've been giving KDE a good honest try for the past couple of weeks. It's definitely very nice if you want the full DE experience.
I went the WM route for a while. At a certain point, it was too much bother getting everything set up Just So. I wanted something that would work and had undergone thorough testing with minimal effort on my part. If I want to tinker with something, I want it to be more interesting than a WM config file.
Moving to Linux sounds cool and is cool until you realize 2 things, one, you can fuck yourself in ways you didn't know possible.
2, windows is dominant and you will lose access to a fair portion of games immediately upon switching.
Unless you really need to lower background bloat, develop code, or got something vehemently against windows, its not worth the swap for 90%+ of the population, you will go back.
I didn't mind the learning curve, realizing the sheer amount of programs and games that have no development plan for Linux was what made me swap back.