I recently noticed that a user mapped several historical sites without any physical representation (like memorial plaque, or anything similar). They are simply places where something historically significant happened.
Looking at the site of the beginning of the first world war, presumably referring to the assassination of Franz Ferdinand:
The plaque commemorating the assassination is already mapped on the north side of the river
This mapper has located the site south of the river - I don’t think any significant event happened there
The tag used is historic=battlefield, which seems like a stretch for an assassination of an individual
The wikidata and wikipedia tags refer to the entire First World War, not to this location or even the event that happened at this location.
I don’t know if this is typical, but in this example there seem to be issues with accuracy and usefulness even aside from the question of whether this kind of thing is mappable.
I would agree with @woodpeck here. These points/sites could be added in their own thematic map. I would not have a problem if user created dedicated wikipage and added coordinates, but not putting it on the general map.
OSM isn’t the only open information database that exists. You can create entries for those events including their location in wikidata for example. That would be entirely in scope there, but it’s not really suitable for OSM.