Don't give up so quick. Most of the issues have already been covered but I'll mention some again.
The dough for deep dish is MUCH different than for other styles. It is more like a biscuit so don't use any high gluten flour. It also has lots of oil. No need to par bake and only use a small amount of butter on the bottom, not the sides. Baking with all of the ingredients together will keep the dough in place.
Here's a great place to start:
https://www.realdeepdish.com/deepdishholygrail/
I've turned out many great deep dish pies based on the formula from that site. I still prefer New York style, but deep dish is so quick and easy to make. Here's an example of a recent pie I made.
View attachment 484352