There are many things that endure today that were invented in another time, things that might not be conceived of today that were borne of the best technology of that particular time. The LP is the culmination of Edison's original invention 137 years ago. The piano evolved out of other keyboard instruments 200 years ago and developed about as far as it can go around 1910.
If the automobile were invented today, the government would almost certainly deem it too dangerous for public use and prevent it from being licensed and sold, except perhaps to an elite few.
I lived in Boston for about a year, and one particularly cold, blustery day, a co-worker arrived in the morning and announced, "I swear, if the Pilgrims had landed in California, New England would still be uninhabited."
Often situations and things are the result of a mindset, a need, a time, and a place. Change any of those things and the "thing" probably wouldn't have happened that way. The LP is just one of those many things.