Here is my line of thought.
Some time ago the FSF discovered that software users could loose their
freedom when doing their computing in others people's computers.
To protect users, the FSF released the AGPL, whose only difference with the
GPL is the following (quoting from
https://www.gnu.org/licenses/why-aferro-gpl.html):
If you run a modified program on a server and let other users communicate
with it there, your server must allow them to download the source code
corresponding to the modified version running there.
Why isn't that clause in the GPL?
