Wikimedia users routinely do null edits when they feel the job queue is not fast enough for their needs. Unfortunately, null edits of templates cause refreshLinks jobs to be queued, which exacerbates the problem they were intending to solve. In the current case, a user null-edited several templates, causing the equivalent of 22 million page parse operations to be queued.
In a previous case, a user caused permanent job queue lag with a bot which regularly executed API action=purge with forcelinkupdate=1, not realising that the updates would be recursive.
I suggest making null edits do only non-recursive link updates, and I suggest splitting the forcelinkupdate API parameter into forcelinkupdate and forcerecursivelinkupdate.