The easiest way to deal with a spammer is to just destroy the account, removing all spam posts with them. This works well in most cases, but it also makes it impossible for moderators to track patterns in recent spam.
In cases of particularly stubborn and predictable spammers, the moderators ask SE for additional measures to block them. To do that they need to collect some information about those spammers, and not just destroy them on sight. One workaround was merging the spam accounts into a suspended user, which then contains all the information needed. This is no longer possible, as moderators cannot merge users anymore.
Such workaround should also not be necessary, as all the information needed is available to SE. What would be useful is a mod-only page listing recent spam posts (= sucessfully deleted by spam flags) and the IP addresses they were posted from. It should be possible to group by URLs contained in the post and by IP addresses. The moderators could then ask SE to specifically block persistent spammers that are visible on that page.