There's already a RevisionDelete and some scary instructions on how to make deletion permanent, i.e. like nuking, from 2008 and involving SQL manipulations that may or may not work with your mediawiki as installed and extended. There's DeletePagePermanently which seems to be functionality equivalent to nuke, on a tab. There's DeleteBatch, etc. which doesn't "really" delete pages.
Given all that, why is there no way to nuke specific revisions through the mediawiki shell tools or tabs? That's what we need to remove spam, SQL manipulations are very likely to leave things in an inconsistent state.
For wikis that are hit with bots that spam pages with legitimate edits, which cannot simply be restored with the correct timestamps after a "nuke", there's presently no solution at all. This can multiply smaller SQL DBs' size by hundreds of times and sure makes wiki farms very difficult to run.
Larger wiki farms like Wikimedia, Wikia, etc., probably have legal reasons to never truly remove anything and can pay to keep expanding disk space.
However if there's a frequent backup regime, or if you're hosting on a proper web host or in the cloud, you are paying for every gigabyte you move... we really need a NukeRevision.php shell tool and extension that lets someone tag spam in the history for permanent irrevocable removal, and purging to get the actual saved size down.