Why is the Hadeon Eon not really considered a part of Earth’s geological history?

Hadean time which was 4.6 to 4 billion years ago was not considered a geological period, Because there were no rocks on Earth that were this old, except for meteorites. When Hadean Time occurred, the solar system was beginning to form with a large cloud of gas and dust that was around the Sun, also known as an accretion disc.