I think about this sometimes because people often post art for characters that haven’t been introduced in the anime yet, and they usually don’t use spoiler tags. While the art itself isn’t a spoiler, someone could comment something that is. For example, say someone’s reading NT9 and sees an Othinus post on here with several people saying she’s best girl. They might be confused because where they are in the story she’s a villain doing some very awful things. What's more likely however is that they'll probably think Othinus becomes good later on, which would sorta spoil the story for them. Even if a non-spoiler post isn't about her, someone could obviously still mention her. Should we have to use a spoiler tag to say something positive about Othinus? That obviously sounds pretty silly but we could be spoiling the story for people that haven't read through her arc