Question: I am wondering what the point of `sh` being symbolic linked to `dash` is? I understand that `dash` is supposed to be faster than `bash`, but I am uncertain why the original `sh` shell isn't present in `sh`. 

Or if anything why isn't `sh` linked to `bash`?

Answer: 
Speed and POSIX compliance ( in other words, portability) are the main factors. Remember that `/bin/sh` is meant for system scripts, which may or may not have come from older versions of Ubuntu and/or other systems. 

Sure, shiny features of `bash` are cool to use for us users, but when it comes to running thing in environment where you have to manage several different servers/systems - having POSIX compliant shell makes whole lot of difference. Especially, if you're a new sysadmin and inherited environment with many scripts.

As for why original Bourne shell isn't present, it is simple - it is a proprietary product originally owned by AT&T Bell Labs. 

Also, there's actually an explicit explanation on Ubuntu wiki about that:

> 
> Why was this change made?
>  The major reason to switch the default shell was efficiency. bash is an excellent full-featured shell appropriate for interactive use; indeed, it is still the default login shell. However, it is rather large and slow to start up and operate by comparison with dash. A large number of shell instances are started as part of the Ubuntu boot process. Rather than change each of them individually to run explicitly under /bin/dash, a change which would require significant ongoing maintenance and which would be liable to regress if not paid close attention, the Ubuntu core development team felt that it was best simply to change the default shell. The boot speed improvements in Ubuntu 6.10 were often incorrectly attributed to Upstart, which is a fine platform for future development of the init system but in Ubuntu 6.10 was primarily running in System V compatibility mode with only small behavioural changes. These improvements were in fact largely due to the changed /bin/sh.
> 
> 
> 

And here's a note about portability:

> 
> The Debian policy manual has long mandated that "shell scripts specifying '/bin/sh' as interpreter must only use POSIX features"; in fact, this requirement has been in place since well before the inception of the Ubuntu project. Furthermore, any shell scripts that expected to be portable to other Unix systems, such as the BSDs or Solaris, already honoured this requirement. Thus, we felt that the compatibility impact of this change would be minimal.
> 
> 
> 

See <https://wiki.ubuntu.com/DashAsBinSh>
In GNU/Linux distributions, the "original `/bin/sh`" is actually Bash.

GNU wanted a Bourne-like shell that was under the GPL, so that's why they chose Bash for their `/bin/sh`, instead of Bourne, which was not GPL-licensed. Modern Linux distros inherited this decision to the point that it became a defacto standard for `/bin/sh` to be Bash. The original Bourne shell ("sh") has been used in other non-Linux Unixes, even as recently as Solaris 10, but it's never been a mainstay in Linux distributions.

Switching `/bin/sh` from bash to dash was a Debian decision (inherited by Ubuntu) motivated largely by speed - it came at a time when they put a huge effort into improving boot speed, and a large part of the boot CPU time at the time consistent of running init scripts.

Bash continues to be used as the default interactive/login shell for users, but Dash is the one at `/bin/sh` and the one which is executed for system scripts such as init scripts.

Dash is very fast, but also is very closely POSIX-compatible - a standard that is aligned closely with the Bourne shell. So in a way, by switching from Bash to Dash we are moving back to a shell more closely aligned with Bourne.