Many MediaWiki extensions shows informational popups, MediaWiki-extensions-GuidedTour tours, invitation dialogs, onboarding material etc. at key points in the workflow. Often these key points are somewhat generic and multiple extensions would trigger popups at the same time (e.g. after registration, after an edit, at the beginning of an edit, when viewing a certain kind of page). Showing multiple notices, often on top of each other, is poor user experience (see e.g. T229887, T254943, T24102, T235566, T189569 for some past problems); there should be some mechanism for prioritizing them and only showing the highest-priority one. Some extensions provide one-off solutions (e.g. the vehidebetadialog URL parameter or the mw.libs.ve.disableWelcomeDialog() function in VisualEditor) but that doesn't scale well.