That was true in Audacity 2.1.0, due to a bug Audacity 2.1.0: FFmpeg required for MP4/M4A/MOV/ALAC import
I would just update to Audacity 2.1.2 from Audacity ® | Download for Mac OS. Then Audacity will be able to import MP4 and other QuickTime formats without FFmpeg.
Gale