In the age of Desktop Siri, this feature could also be very risky to ship if it fails for the masses the same way as clippy, the MS word assistant, failed 20 years ago.
Apple bought Cue in order to bring the "surfacing what's temporally relevant to the user" experience to Siri. I don't really see much of what Cue worked on manifesting in Siri since the acquisition, except for the Siri watchface for Apple Watch.
https://www.cultofmac.com/248525/why-apple-bought-cue-hint-t...