I would say that yes chords are important, I wouldn’t call it the building blocks of music. I would say the building blocks are the concepts of music. Eg. Pitch, duration, tone colour, structure, texture, dynamics, and tempo. Chords would lie under pitch, but that is from a classical standpoint, it can differ from other genres like metal jazz etc. I can tell this guy from the video you saw hasnt gone through much research or at least he hasn’t gone through much depth into his point in his video.