The problem is when I decide to stream this game, I watch a concert, then I get 3 people spamming anime boobs, or worse, on my screen. That means I'm not allowed to watch symbol arts any time I decide to stream because a small fraction of the community are edgy manchildren and it's unfortunate I can't look at funny symbol art or share them.
Well technically when you stream, that's your contract with Twitch(or whoever) and you guarantee it'll be safe for their audience. That's not SEGA's job (although it is in their interest). You're the one broadcasting the game to another platform.
And as you said you can always just disable symbol arts and block the chat with a facecam/picture just like other streamers do.