[bo1024]

Not common that you see a philosophy more radical than Stallman's.

As I understand Stallman's free software philosophy -- the GPL -- the idea is that code must respect the person running it / using it.

Under this philosophy, if I am communicating with you, it's not up to me what tools you use in formulating your responses. And whether those tools respect your freedom or not. So GPL only applies to those directly using the code, not others they interact with using the outputs of that code.

I'm wondering if the AGPL is supposed to come from a different philosophical foundation, or if it would be better understood as an economic / power-structure tool?

[pornel]

SaaS is a workaround for GPL, and AGPL is a bugfix for that.

Nowadays people run code remotely, and GPL didn't take that into account. AGPL is still about giving users freedom to control the code they use, and works regardless whether the code is run on a local machine or a remote server.