Unless you set /bin/dash or /bin/sh as your shell you weren't using dash(interactivly). /bin/sh is just a symlink to /bin/dash so dash is only used for scripts with #!/bin/sh at the top.

Even root has /bin/bash as its log in shell.

/bin/dash is more like the original bourne shell which helps people write more portable shell scripts and it's faster(especially for startup).

Dash is also /bin/sh in Debian.

I'm pretty sure even unix V6 had > 11 binaries, http://man.cat-v.org/unix-6th/1/

maybe some systems using busbyox may have < 11 binaries.