Why must a PPA Label change be explicitly accepted in `apt`?

As discussed here, if an apt PPA changes its label and we try to apt-get update, we get something like this:

E: Repository 'http://ppa.launchpad.net/ondrej/php/ubuntu artful InRelease' changed its 'Label' value from '*****
The main PPA for PHP (5.6, 7.0, 7.1) with many PECL extensions *****' to '*****
The main PPA for supported PHP versions with many PECL extensions *****'
N: This must be accepted explicitly before updates for this repository can be applied.
See apt-secure(8) manpage for details."

The solution is to run apt update instead and manually accept the change.

This question is about the reasoning. Why is it important that the label does not change without my explicit awareness? I don't know where I would even see this label in normal day-to-day usage...

Solution 1:

You get this warning when the PPA owner changes the name of the PPA, and apt wants you to know that.

I can think of several reasons how this can be helpful.

1. The PPA owner might want to discontinue the PPA, and they can change the name to something like the following to notify you. "PPA for X (discontinued), use another method to get this software"

2. The PPA owner might add additional software to the same PPA, and the updated version of that software might break someone's workflow (suppose someone decides to put a later version of gnome-shell in a PPA for cheese). By changing the name, they can warn you so that you can decide whether you really want to continue using this PPA.