Careful to differentiate between recording, mixing, and mastering functions/studios. 99% of those professionals use active speakers. Their priority is the speaker itself, not the amps used. Home listeners keep wanting to tweak performance of their gear (while neglecting vastly more important issues, but that's a different topic).
Recording and mixing studios are typically small. Near-field listening with speakers on a shelf/desktop. No room for tall 3-ways or 6 channels of external amplification and no desire to add all the wiring needed for all those external amps on top of what they're already dealing with. And the good workers often bring their own monitors, so portability is an important consideration. So smaller active 2-way monitors dominate recording/mixing studios.
Mastering studios are typically setup in larger highly treated rooms with more of a far field setup. That's where 2-way and 3-way floor standing speakers are used professionally. Controlled directivity, low thermal compression, and deeper bass output are added to the criteria for good speakers under these conditions. And yes, the JBL M2 does use external amplification, partially because Harmon International owns both JBL and Crown, but also partially because space and wiring are of less concern.
