When you’ve met someone, you develop a form of personal, intimate connection. When they die, you begin to feel a form of grief & your brain does a quick pass over what grief you need to experience. The closer you were to them, the deeper the grief. If you didn’t know them at all, there is NO connection so NO grief.
I don’t know about you but grief is one emotion I block at all cost. Once my brain passes on the idea that NO grief is required, I can block it really fast. I might feel a brief sadness that somebody lost a loved one, but it doesn’t require grief from me…hence I skip it out of self preservation. If I knew them then my brain turns it over to me as to how much grief is required & I process from there.