The idea of Free Software, at its most extreme, exists as a useful endpoint of an "Overton Window" for software. Which is to say, all software benefits from its existence even if they don't e.g. sign on to the GPL. You're forced to consider it as a possibility.
Without it, we'd probably think of "Open Source" as the most "open" software can be -- which, as OP proves, is quite wrong and nebulous.
