Answer:
Because it was very difficult to get.
If I understand correctly that you're speaking of France, then the formation of National Assembly has effectively brought an end to the Estates-General.
Before, all three states (the Estates-General) needed to be taken into account, but the National Assembly (mostly composed of the third state, the common people) later was the only organisation needed,abolishing the need for the other estates to congregate
Jetstream hope this helps out
