Rate limiting move-subpages was proposed in T16356 but not implemented because it was thought to excessively limit autoconfirmed users' ability to move subpages. It turned out that this was abused for page move vandalism anyway, so it was restricted to sysops. Making this rate limited and available to autoconfirmed users would greatly help on projects like wikibooks since books have plenty of subpages, and help in general on all projects with talk subpages and template/module moves, without any increase in risk. Using the rate limit would also easily allow to increase the limit for a particular trusted usergroup, such as reviewer on wikibooks.