That doesn’t get stored in git, you won’t be able to see that information on the clone of the repository you will be developing on locally.
1. The reviewer
2. Someone scanning commit logs for patches of interest
3. Archaeologists
Archaeologists are people a year, five years, 10 years down the road who are trying to figure out how the code got to be the way that it is, so they can feel confident changing it. (See also "Chesterton's Fence"[1].) Those people should not have to dig out the conversation from some random PR to figure out what's going on.
Not knowing to look to an associated PR thread for a commit would be the equivalent of modern day archaeologists not knowing what "carbon dating" was.