Anyone have a different opinion?
why is the chess king active at the end of the game?

The king becomes very important in the endgame. Compared to the previous phase, the king must be more active, often moving to the center or near critical areas to help attack or defend.
good
In the opening and middlegame, there are many pieces on the board that can attack the king. If your king gets exposed early, you may lose to a mating attack.
in the ending, much of the planning concerns queening an extra pawn. Now, because there are not so many pieces on the board, king safety is less of a concern. How can you escort your pawn to the queening square? You have to use your remaining forces. It is at this time that the king becomes an active piece.
The king becomes very important in the endgame. Compared to the previous phase, the king must be more active, often moving to the center or near critical areas to help attack or defend.