What Sony said about their SSD was that it enabled game developers to not duplicate assets like they did for rotating storage. One specific example I recall in Sony's presentation was the assets for a mailbox used in a Spider Man game, with hundreds of copies of that mailbox duplicated on disk because the game divided Manhattan into chunks and tried to have all the assets for each chunk stored more or less contiguously.

If the Helldivers devs were influenced by what Sony said, they must have misinterpreted it and taken away an extremely exaggerated impression of how much on-disk duplication was being used for pre-SSD game development. But Sony did actually say quite a bit of directly relevant stuff on this particular matter when introducing the PS5.