Great, you have a list of dictionaries of dictionaries. Now the user has updated some of the items inside one of the nested dictionaries. The user clicks save.

Great, you have a list of dictionaries of dictionaries. Now the user has updated some of the items inside one of the nested dictionaries. The user clicks save. Now what? You've got to get that change to the data in the dictionary inserted into the correct place in the relational database. You're going to write code to do by hand what an ORM wants to do for you.