> This example exposes the "uninitialized" state that a property can be in, which is NOT the same as NULL. This distinction frustratingly comes up when you try to do a null check on these properties:

If you're accessing an uninitialized property or checking if a property is uninitialized, you're probably already doing something wrong.

The point of class properties with no default value is that you're supposed to set them either in the constructor, immediately after creating an instance, or via some other method that guarantees they'll have a value by the time you need to read them (such as deserialization with validation).

If you want your properties to have a default "unset" value that you can trivially check for, that's what null is for. The author doesn't make it clear whether they are aware that you can declare a nullable string and give it the default value of null, but I hope they are.