Gadgets with only styles and dependencies ignore the dependencies. This is a rare but plausible usecase.
A set of gadgets on Polish Wikipedia is affected by this:
https://pl.wikipedia.org/wiki/MediaWiki:Gadgets-definition
small-sections [ResourceLoader | rights=hidden | hidden | dependencies=mediawiki.user,user.options] | small-sections.js small-bibliography [ResourceLoader | dependencies=ext.gadget.small-sections] | small-bibliography.css small-external-links [ResourceLoader | dependencies=ext.gadget.small-sections] | small-external-links.css
small-sections has some JavaScript to mark up sections by specific name on all pages, and the remaining gadgets provide alternative styling for those sections.
This is a regression from T42284 / https://gerrit.wikimedia.org/r/308096.