There's two versions of simple here:

• Mac OS/Windows "simple": everything works out of the box. All the technical details - and I do mean ALL of them - are smoothed over so you barely have an idea of how the system works unless you go digging. This is good or bad depending on how you look at it. Good in that it's easy for the average idiot to use, but bad in that it results in more idiotic idiots over time. Also, bloat, tons of bloat.

• Arch "simple": you get only what you absolutely need. Anything beyond that like a desktop environment is all up to you to get working.

Both of these can be simple from the user's perspective if they're prepared to deal with the appropriate consequences. Windows is "simple" in that it just works pretty well straight out of the box (well, except for the occasional driver install, but we don't really talk about that). The same goes for Ubuntu - it's simple to get going with, anyone could learn it quickly. Arch is its own "simple", in that you only get the core of a functioning system - a clean slate from which you can build your own environment.

I view it as the difference between working in a professional workshop loaded with every tool you could possibly imagine vs. working in a pretty bare-metal environment with only a few of the basics. Sure, that professional workshop looks really fancy, but I bet it cost a lot... and really, all I need is a bunch of screwdrivers to do most of what I want anyways.