[all variants] Samba security questions

So I was asking myself how secure is setting up Samba for sharing files within my local network. Stumbled upon a rather interesting video from Nixie Pixel (https://www.youtube.com/watch?v=-wUfzdiE4m8), but not sure if all steps described in the video are really necessary (or even what they mean). So I'll start listing some of the steps and questions below:

- Do I really need to create a new user account just for samba (e.g "sambaguest") ?
- Is it really necessary to disable /bin/bash for "sambaguest" ? And what does it even mean?
- What are the disadvantages (or possible threats) to not doing such procedures described in the video?

Any additional information on the matter is pretty much welcome!

Thanks!