why does the author rely on `pv` when `dd` has a status flag to display its progress already
Not all versions of `dd` support the status argument. I think it’s particular to GNU. If you’re working in a shop that runs multiple versions of Linux as well as multiple versions of proprietary UNIX then you tend to use the command that works everywhere rather than remember the exceptions for each. (I worked in a place that ran all of RHEL, SLES, Ubuntu, AIX, Solaris, and SCO UNIX).
Not all versions of `dd` support the status argument. I think it’s particular to GNU. If you’re working in a shop that runs multiple versions of Linux as well as multiple versions of proprietary UNIX then you tend to use the command that works everywhere rather than remember the exceptions for each. (I worked in a place that ran all of RHEL, SLES, Ubuntu, AIX, Solaris, and SCO UNIX).