What is the point of OOP visibility in PHP when Closures and Reflections are available?

Consider this code here:

final class TinkerWithMe {
    protected $key1 = 19;
    private $key2 = 88;
}

$class = new TinkerWithMe();

$getKeys = function() {
    return array($this->key1, $this->key2);
};

$oldKeys = $getKeys->call($class);

$newKey1 = 96;
$newKey2 = 42;

$setKeys = function() use ($newKey1, $newKey2) {
    $this->key1 = $newKey1;
    $this->key2 = $newKey2;
};

$setKeys->call($class);

Why bother with OOP visibility when you can get around it so easily with Closures or Reflections?

Is there a way of blocking this kind of thing that I am missing?