Can a hobbyist ARM setup be as simple as this AVR one?
ARM microcontroller development is a little more complex. But, only really because DIP packages are generally not available.

If you're willing to use a development board, ARM development can be even easier.

The mbed is an ARM microcontroller on a breadboardable DIP shaped board.

The C/C++ compiler is web based and the board appears as a USB mass storage device. You download code by saving from your browser to the mbed. Even easier than a basic AVR setup.

Once you outgrow this setup, you can run gcc locally on your PC and still upload via USB. After that, you can move to JTAG using OpenOCD.