Replacement of entire disks to grow the pool is simply a different way of adding capacity, because ZFS is based on different paradigms than what one is used to

Replacement of entire disks to grow the pool is simply a different way of adding capacity, because ZFS is based on different paradigms than what one is used to with run of the mill implementations; however, in practice, it's a much simpler and therefore much more reliable way to extend capacity. The units are simply entire larger disks. Swift is also how many orders of magnitude more complex?