I inquired about this and was told this works this way "by design" but if this is true this is pretty bad design in my opinion.
The problem is that when I'm in the 'Communication' tab on a very active ticket, it's very confusing because interspersed with the communication (posts by the user and replies by the agents) are COMMENTS.
Well, there is a 'Comments' tab, if I wanted to view all the comments on the ticket I just need to look there.
Having comments in the "Communication" tab is extremely cluttering, and technically 'comments' are not 'communication' as they are not replies to the ticket.
Comments should not be showing up at all in the Communications tab ('Sticky Comments' would be OK to show there and that would be useful) but otherwise it just clutters the ticket needlessly.