Right now it is not possible to tag a team member inside a story or comments, sometimes we need to mention or attract the attention to someone else to a story, to answer a question, confirm an approach or simply ask the status. Usually, in other story management tools this can be done. At this moment, we need to remember to reach out to the team member aside while providing the story ID.
definitely a draw back of sprintr that @mention users is not available to having the target person alerted by mail as example.
I agree, this story sort of relates to your idea.