Despite what the marketing might have said at the time, Ratchet & Clank: Rift Apart coming to PC seems to have put the entire SSD discussion to bed, once and for all. A solid-state drive is officially listed as "recommended" rather than being required to run the game on minimum settings.
Much was made of the game's fabled ability to load content near-instantaneously, a feat to which console gamers have quickly become accustomed in the years since. Insomniac creative director Marcus Smith let the poorly-aged quote slip in a video posted on PlayStation's YouTube channel (thanks VGC) prior to launch, stating that:
“Ratchet & Clank: Rift Apart is a game that utilizes dimensions and dimensional rifts, and that would not have been possible without the Solid State Drive of the PlayStation 5."
That said, over on the PlayStation Blog, Nixxes Software (responsible for this particular port) strongly recommends that you do enjoy this one with an SSD, noting: "While Ratchet & Clank: Rift Apart can be enjoyed using an HDD and the minimum system requirements, we encourage players to use an SSD in combination with the recommended system requirements or higher, to experience the game’s signature dimension-hopping gameplay as originally intended."