Thread:Sannse/@comment-44575031-20210125095027/@comment-8-20210125173454

There are many reasons:


 * Their conversation, or an argument, may be disrupting the wiki - for example by leaving many posts in a short time.
 * They may be off-topic on a wiki that is on-topic only.
 * One of them may be harassing the other. For example leaving unwanted messages - especially when asked to stop.
 * One of them may be bullying the other, and have been told to stay away.
 * Both may be starting arguments and won't stop.

Then there are past problems like sockpuppeting. If someone already banned comes back to talk to another person, and if they both know about the ban, then they could both be blocked.

There are lots of other situations, but I think that's the most common.