I have worked on graph systems with direct support for temporal relationships. Time is typically handled in the same way it is with ordinary systems that handle

I have worked on graph systems with direct support for temporal relationships. Time is typically handled in the same way it is with ordinary systems that handle a lot of space-time data. These were all closed bespoke systems, as tends to be the case for high-scale graph apps. I would agree that off-the-shelf graph systems tend to have weak or nonexistent temporal relationship support. While it may not be obvious, graph and spatial data models are often represented with the same data structures at scale, but use somewhat different algorithms over those structures. The temporal bits are pretty vanilla unless you need bitemporal support or need to find unusually complex temporal patterns.