Besides, from a UX perspective, a list of property names in autocomplete looks much more readable than a huge list of initializers caused by all possible default parameter combinations. Some initializer combination possibly won't even fit in autocomplete list because of the length, but it's also much hard for a user to find a matching combination. Here's how autocomplete looks for long initializers in Xcode:
You can't see all of the parameters, in addition to the fact that it displays only one of all possible initializer variants. Even if all possible initializer variants were displayed, it would be very hard for a user to pick a correct one.