It has it’s advantages. For one it’s so small you can fit it on a keychain and wherever you go you have everything you need.
A bootable USB is a bit less convenient since you have to restart the computer to boot to your dev environment.
A small laptop would be perfect, but I can’t really afford one right now. Maybe in a few months. I actually need to replace my old iMac (mid 2007, yep that old) and upgrade it to something like a Macbook pro