HDDs are a huge bottleneck on system performance when you are processing large data volumes, so it's hardly a surprise that software is increasingly designed with SDDs in mind.
If you have a great deal of patience, and like looking at loading screens, area transitions are OK on HDDs, but only if the game assumes the use of HDDs in its design. But, increasingly, cut scenes and cinematic dialog require enough data that the game experience without an SSD will be quite poor, and the only "optimisation" that would improve this is to heavily reduce the quality of the assets being loaded. More recent developments, like auto-LOD systems ( e.g. Nanite in Unreal Engine 5 ) will continue to ramp up the data rates needed from storage devices beyond what a pure HDD can sustain.
If you are not using SSDs in your system, it is the single most effective quality of life upgrade you can apply. Even the worst SATA SSD is 10-100 times quicker than a normal HDD, depending on what it is doing. If you are able to use NVMe SSDs, the benefit is much greater, although they are more expensive. At the current prices you can get SATA SSDs for about $50/1TB, which is worth the investment, even on older systems.
As @Icelyn says, you dont need to discard your older drives, just add an SSD, and shuffle the games you are currently playing onto the SSD.
