This seems like overengineering and a needless application of OOP. The author presents ideas like service classes or static factory methods as if they are self-evident, but I don't understand what would make someone write TypeScript code this way besides too much Java experience. The final solution has the value of the “name” field nested multiple objects deep!

How about this code instead:

    export interface User {
      readonly name: string;
    }

    export namespace User {
      export function validate(user: User) {
        // In "strict" TS, `name` is required at compile time to not be null or undefined.
        if (name.length < 2 || name.length > 100) {
          throw new Error('User must be greater than 2 chars and less than 100.');
        }
      }
    }

Unlike the OOP solution, there's no guarantee that any given `User` is valid unless you check it with `User.validate`, but there should be minimal places if not one single place where users are actually validated, such as where they are saved to the database or backend.