The Altair didn’t come with a keyboard or screen. Just a front panel with lights and switches (like a PDP-11, to be fair). So, the fact that it wasn’t an integrated system in one box all from the same manufacturer distinguishes it as a Mini/Micro Computer rather than a Personal Computer.

Yup. That's why you hear of the Apple II as one of the first personal computers, and not of the Apple I, which was a more advanced kit than most, but still required owners to supply their own case, power supply and keyboard.