Humanitarian OSM Tags/operational status
Argument against is that the absence of a disused=yes tag does not implicitly confirm that the feature is indeed open. It is important in disaster response to know if a school or hospital is indeed operating at a time.
Argument for is that if source=survey is present and disused=yes is not than it can be extrapolated that the survey confirmed it was open. This may not be sufficient if the surveyor surveyed the feature not during opening hours, or simply forgets to note this.
The disused prefix (e.g. disused:amenity=hospital) can obscure very valuable data, as standard maps won't render it.
Please note that the current concept for mapping disused and abandoned tags is to use these as prefixes to create a whole namespace, and not as attributes like this page suggests. You can find more information on the pages that are linked above, i.e. disused=* and abandoned=*. The main disadvantage of attributes is that all data consumers (renderers, routers, etc) will have to check your new attributes to know if the feature is okay or not, which is not backward compatible.