Why are epitaphs on headstones so brief, minimal, and contain little to no biographical information about the deceased?

I'm astounded that some people have lived such prolific noteworthy lives, were world-famous for decades, contributed so much, made life-changing inventions that the whole world benefitted from ...

Yet the only words on their headstone are like "Dad, Brother, Son, We love you."

Like WHAT?? He invented the xyz and had the leading role in 300 Hollywood films & 20 Guinness world records & discovered the cure for xyz and on & on ...

Why not mention any of that on their headstone?