Personally, I think that either tanks and healers getting most comms is a misconception, or there truly has been an over correction the other way based on that misconception. Most of my comms are actually from when I mained BRD. My healer comms.... eh, it seems kind of random. One dungeon I may do amazing, straight carrying the dps through it, and keeping a very squishy tank alive. And... zero comms. Another I may be running as SCH to get a bit of practice with my least played healer job, and walk away with 2.

Part of it may simply be that fewer people even comm at all anymore.