Options for eliminating NULLable columns from a DB model (in order to avoid SQL's three-valued logic)?

Question

Some while ago, I\'ve been reading through the book SQL and Relational Theory by C. J. Date. The author is well-known for criticising SQL\'s three-valued logic (3VL).

Answer 1

Option 3: Onus on the record writer:

CREATE TABLE Person
(
  PersonId int PRIMARY KEY IDENTITY(1,1),
  Name nvarchar(100) NOT NULL,
  DateOfBirth datetime NOT NULL
)

Why contort a model to allow null representation when your goal is to eliminate them?