Rather 89% PC players have an SSD. For the console players much less. People (read: hordes of kids) are still using PS3, PS4, etc.
And only a very small portion of that 11% have ONLY an HDD but now that it’s only 23gb it’s easier to justify using your precious SSD space for it.
Which doesn’t matter at all in the case of Helldivers 2 as it’s only available for PC, PS5, and XBS/X. That’s a good part of why PC players were so irritated, actually: when all this blew up a few months ago, the PC install sizes was ~133 GB vs the consoles’ 36 GB.
Helldivers 2 is only on current gen consoles so older ones are beside the point, the current ones use NVMe SSDs exclusively. PC is the only platform where HDDs or SATA SSDs might still come up.
I think they were talking specifically about this game, which is only available on PS5 and PC.
Edit: Forgot it was released recently on Xbox Series consoles but those also have SSDs.