You'd have to expand more on your proposal for using a dictionary for people to be able to reply. The article was full of use cases, so why not address those rather than simply state that you can't think of any?
When you say use a dictionary, do you mean subclass `dict`? One of the aims of the project is to constrain the available instance attributes, as in a normal class. How would your dict proposal do that?
I think the point is that this is basically a normal class, but one with the boilerplate already written for you. If you don't mind boilerplate, this library does nothing for you. If you don't want to write classes and think dicts are good enough, this library does nothing for you.
If you do want to have classes but don't want the boilerplate that comes with making a basic-but-full-featured class, then that's where this library comes in.
When you say use a dictionary, do you mean subclass `dict`? One of the aims of the project is to constrain the available instance attributes, as in a normal class. How would your dict proposal do that?