Domain concepts represented as raw strings, numbers, or booleans — phone number is a string, money is a number, status is a code.
Each domain concept has a small typed home — Money, PhoneNumber, OrderId, Status — that knows its rules.
Smellier version
function priceFor(cents, currency) {// ...}
Fresher version
class Money { /* amount + currency, with arithmetic */ }function priceFor(money) {// ...}
Validation and formatting scatter across every consumer; the type system can't catch wrong primitives in the wrong slot.
Each wrapper class adds construction ceremony at every entry point; for one-off primitives that never carry domain rules, the wrapper is overhead with no return.
Misuse becomes a type error; behavior accretes around the concept; refactoring is local to the wrapper.
Wrapping every primitive on principle — Name, Title, Description as separate classes whose only methods are toString() — adds typing ceremony without enforcing any domain rule.