[zekevermillion]

This is a better summary of the key issue than any I've read from a lawyer.

The root of it is that the copyleft licensing scheme was from the beginning merely a clever hack. Ideally (from a free software perspective) copyright law would not protect functional software, and we would have another law that requires all published software to be free software.

The GPL was a speculative attempt to bend problematic copyright laws to the purposes of free software. Over time the GPL has proven to work, sort of. But it was not clear at the beginning that it would. Years, decades, have gone by and we now see that there are ways for companies to restrict user freedoms with software that technically complies with the GPL. The GPL was pretty successful for the 1990s concerns, why not make an updated license that addresses 21st Century business models. It is still not clear whether the AGPL will work as well vs SaaS as GPL did against the "selling copies" model.