Ya, I wouldn't want to play it off an HDD. It's still a bit less than I thought as it's 'only' twice more than Doom Eternal does in a similar amount of time.
The most IO intensive thing I've tried yet was actually the Matrix demo (edit: the open world part) which read ~100GB over the span of 10 minutes. That's also a pure streaming test while my R&C test above includes cutscenes etc.
Not intending to downplay the significance of consoles getting SSDs, but that example is terrible.
Console SSDs do the biggest work when they need to read lots of data in a short time. Accumulating reads over time undermines their work.
185GB in 30 minutes is a average of 103MB/s and 100GB in 10 Minutes is roughly 167MB/s.
If you google average HDD speeds, it spits out between 80MB/s to 160MB/s depending on HDD obviously. If you even settle in the middle, you have 120MB/s, which is enough to satisfy R&C demands (averaged out).
I don't know when most reads happen, for RC I'd assume it's when jumping rifts, loading a save etc. but those would only take longer on HDDs than SSD.
I also can't say how the Matrix demo handles reads, if it does constantly, in bursts etc. but as you can see it's only barely above average and probably within higher end HDD read speeds.
That's not including HDD caches for repeated read calls etc.
Until we ever get a game that was build with SSDs in mind that also releases on PC, we will never be able to tell how any game behaves when put on HDD.
RC could have micro stutter as it waits for data, or it could simple have pop in, or it would only load longer and have higher RAM usage to push constantly called data in there. Who knows.