Accounts cannot currently be blocked globally, so that stewards must lock users out of their accounts to stop them. This leads to a range of challenges:
# Locks are opaque and confusing: they did not initially give an error message -- from the user's perspective, their session simply disappears and their password no longer works. This makes locks impossible to appeal or understand for users, which exacerbates the situation of false-positives.
** It would be beneficial to let stewards block accounts, with an appropriate you've-been-blocked message when they try to edit or create/unify local accounts. [//NB: this may be improving as of 2023//]
# A global block can be locally disabled if needed, or time-limited (we can workaround it with [[ https://meta.wikimedia.org/wiki/Steward_requests/Permissions/Approved_temporary | something like this ]], but this is currently not used in practice).
** [[ https://meta.wikimedia.org/wiki/Steward_requests/Global/2023-w29#Global_lock_for_Q28 | Here ]] is a case that could use a short-time global block (instead of a global lock).
# Global locks were designed for troublemakers that aren't usually worth a second chance, such as spammers, LTA sockpuppets, globally banned users and the like. However, they are also the only global recourse for less severe cases like blocking non-VOA users ( [[ https://meta.wikimedia.org/w/index.php?title=User_talk:AmandaNP&oldid=24184295#Why_have_you_globally_banned_PlanespotterA320? | example ]] ), so appeals may be expected.
** Having a Meta user talk page open allows blocks to be discussed on Meta; not possible for locked users
This is also useful for the #temporary_accounts project, as locking a temporary account would mean that the user will just create a new temporary account on their next edit. By globally blocking them, it prevents edits without logging them out.