By using chat commands, a streamer or mod can ban and block a user, which is good if there is a need to remove someone from the chat, but I believe there should be an option to report a user in a similar fashion, for example:

/report [user] [reason]

With many bans and blocks relating to bots and the recent rise in IP grabbing/unaccessible bot channels, I believe there should be an alternate way to report the user.