You’ve missed out on the biggest feature in PHP 8. With named arguments it’s now possible for arguments to be provided in any order. You can now have functions with a large number of optional parameters, without creating a total shit show.

Instead of writing this:

$product = $productBuilder
    ->setId(101)
    ->setName('iPhone 13')
    ->setPrice(999.99)
    ->setDescription('New iPhone 13 with A15 Bionic chip')
    ->setManufacturer('Apple Inc.')
    ->setInventory(1000)
    ->setDiscount(10)
    ->build();

You can now do this:

$product = $productBuilder->set(
    id: 101,
    name: 'iPhone 13',
    price: 999.99,
    description: 'New iPhone 13 with A15 Bionic chip',
    manufacturer: 'Apple Inc.',
    inventory: 1000,
    discount: 10
)->build();

Sadly, no explanation whatsoever of why this approach might be better than just building the object yourself. The example provided is fairly trivial and doesn’t seem to justify using a builder.

Also, how would you do validation of properties (or even detect incompatibility of some of them)? Surely, because Product can be created directly, the Product class itself should validate its values. But it also makes sense for the ProductBuilder to have its own validation, right? Would that mean doing the validation twice?

The article tries to sell the pattern as being your best friend, but at the same time doesn’t say how that’s gonna happen.