As opposed to JSDuck's MediaWiki core documentation, JSDoc's doesn't show members inherited from OOUI.
Compare:
- https://doc.wikimedia.org/mediawiki-core/REL1_41/js/#!/api/mw.widgets.TitleInputWidget
- https://doc.wikimedia.org/mediawiki-core/master/js/mw.widgets.TitleInputWidget.html
The last one only has methods overridden in mw.widgets's class, and even those have no description.