When I am called on to do a funeral or memorial service, one of the things I always do is call the family together for a meeting. We plan the service and tell stories about the deceased. Every time I do one of these storytelling sessions, the same thing happens. People in the room who knew the deceased will say, "I didn't know that."
Weeks after the service when I talk to the family about how they are doing and what their take aways from the memorial experience were, they often say a similar thing. "I never realized all the things that father did, or what he meant to people." They had learned things about their loved ones from people who came to show their respect.
If you have a loved one, probe deeper. Get to know them better. Ask questions. One day you'll be glad you did.