Hey Mythicalish,
To answer your query, I would not say that it is expected, from your class/spec specifically to dispel bad stuff, but at the same time, I personally try to use various abilities to make the life of the other people in my group easier. Like Papudeath mentioned above, with demanding content like progression raiding in Mythic raids or very high Mythic+ dungeons, it would be best if you use everything in your arsenal.
It is definitely not accepted to have someone name calling you and harassing you, and I would suggest that if this happens again to report them, by using the appropriate function - right-click their name and select the option that suits best.
Additionally I had to slightly edit your post by removing the name of the offender. Naming and shaming is not allowed in our forums, so please avoid doing so in the future.