When we added the ?page= parameter to paged media, the content in the RESTBase cache was still missing this. We added a hacky workaround to prevent RESTBase from concluding that the page= parameter had been deliberately removed when given an <a href="...."> in a figure which was missing the page parameter.
Once the restbase cache expires, we should remove this workaround, so that an editor can indicate they wish to remove the page parameter from a figure by removing the ?page= portion of the URL. We should also take a look at VE's handling of paged media and ensure it matches the new conventions.
In theory Structured Discussions could also have old page option markup, although the combination of paged media being very rare on talk pages *plus* editing of existing (old) comments being fairly rare, means that the corner case that would cause the page option to be lost is well off in the long tail.