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Are the required additional steps that not mentioned within the tutorial due to Django updates?

EDIT: WOW I just realized I've been speaking to this forum under the wrong impression that it was dedicated to the Django Girls Tutorial that I am going through. I apologize to the forum/mods for any confusion it may have caused. I will be taking my questions to an appropriate forum.

I am currently using Django 1.9.
I believe the tutorial uses an older version. Within the 'Deploy!' part of the tutorial, for example, one of the steps that was required of me in order to render my homepage, but not mentioned in the tut, was the necessary inclusion of '<yourAccountName>.pythonanywhere.com' into the 'ALLOWED_HOSTS' lists within settings.py.
Two chapters later in 'Django Views', again you encounter a non-mentioned 'DisallowedHost' bug before the 'TemplateDoesNotExist' bug.
The error suggests that I

add '127.0.0.1' to ALLOWED_HOSTS.

in order to fix the bug and continue with the tutorial. Has something fundamental changed throughout the updates causing this extra step? Am I doing something else wrong entirely?
Looking up the IP 127.0.0.1, I see that it is a 'loopback' address to allow rendering of the webpage on my own local computer. Why was this not necessary before? Can someone ELI5 to help me understand what is going on?

ALLOWED_HOSTS only has an effect when you have DEBUG mode for Django versions less than 1.9.11 and 1.8.16. In later versions, ALLOWED_HOSTS is always checked: https://docs.djangoproject.com/en/1.10/ref/settings/#allowed-hosts