It is hard to see messages from important people such as mods, other streamers, mentions etc. in the chat in crowded chats. An option to filter specific groups would be great. Sometimes streamers try to interract with their friends in their chats but it is hard to see them while people are spamming. Also it would help viewers understand whats going on, who are they talking and waht are they talking about etc. Some people dont want to interract with other viewers in the chat and seeing only mod/vip/mention messages would be great for people that dont want to see other people's messages.

https://twitch.uservoice.com/forums/310201-chat/suggestions/43149558-tagging-messages
This could cover that. Let me know what you think and please vote for it.

allow users to pay for individual messages in a separate 'vip' chat that all other chat members can see, for large streams with thousands of people watching. moderate these messages to exclude ads and so forth. rake in the cash. basically, when super large streams happen, there is no chat because its just an ocean of memes and one word reactions and emoticons etc. and im aware that people can currently do this, like make a donation and the message is seen on screen, and that thats up to the streamers discretion. but im talking about giant streams with tens of thousands of people watching, there needs to be a separate thing that doesnt interfere with the screen or game being watched, but that all of the twitch chat can see, like a separate chat box or something. and the chat in that box will move much slower because only people who pay or maybe mods or announcers or something can write messages in there.