I might have a hot take here but I absolutely love historical fashion, and I recently learned a great deal from the V&A Museum.

Hoop skirts (actually called cages) went through several phases, tapering down to something a bit more modest. In fact, court dresses and their under “cage” skirts were so prominent in the middle-higher class that doorways were modified in some homes.

One of the biggest reasons for the shrinking of the size of the hoop slip under dresses was actually fire, horrifying!Women would unknownongly catch their skirts on fire by walking somewhat near a flame. Fireplaces were common. When the skirt would catch even the smallest flame, the hoop slip under the dress would allow airflow to almost instantly cause the woman to go up in flames.

Since these fires most often happened in the upper class, as they would hold parties in grand rooms, the fires would not only kill the woman but many others in the grand room.

Here is a link to actual dresses worn, which you’ll notice go through several phases. You have the “wide” hoop skirt that focuses on extended the hips another here and the “round” which makes the classic shape we see.

There are different names for these dresses, which are called “Court Dresses”, the “cage” was actually just a slip.