Comment by throw0101a

> ... but in the broader world where multiple options are available at every level it's still bad engineering.

When Sun added ZFS to Solaris, they did not get rid of UFS and/or SVM, nor prevent Veritas from being installed. When FreeBSD added ZFS, they did not get rid of UFS or GEOM either.

If an admin wanted or wants (or needs) to use the 'old' way of doing things they can.