Manual:$wgBlockDisablesLogin/ru

Подробности
Если активировать данный параметр, то сессии для учётных записей всех заблокированных участников будут сброшены, и все последующие попытки логина в них будут неудачными. At runtime, any extra rights blocked users might have are removed as well (which is relevant when the blocked user has an already existing session).

Примечание
When using this with a public wiki, or a wiki that allows unregistered editing, the effect of logging out registered blocked users may actually be adverse. Unless the user's IP address is also blocked (whether directly or via autoblock), logging the user out will again allow reading and editing as an IP address.

Alternative
An alternative to this setting might be using with   to create a group that revokes certain rights.