I think what GP means by "user freedom" is that the software acts in the interests of its users rather than the interests of its developers. Some proprietary software does do that, but there's an inherent conflict of interest there since the developer has a monopoly on the ability to control said software. Software that is open to user modification (which is how I would personally define Free Software) protects against this conflict somewhat by creating a free market for patches to the software, and free markets are much better at aligning with consumer interests than monopolies.
Stallman goes further than my preferred definition, insisting that Free Software must also be freely redistributable with no required payment. This cripples that very same market for patches by greatly limiting the resources available to fund it, and cripples the software itself if there's no big commercial interest backing it. The result is that Free Software is often not competitive with proprietary software, except when it does have a big commercial backer (Chromium, AOSP, etc) in which case that developer is often able to maintain a virtual monopoly on patches despite it theoretically being open to competition.
Stallman goes further than my preferred definition, insisting that Free Software must also be freely redistributable with no required payment. This cripples that very same market for patches by greatly limiting the resources available to fund it, and cripples the software itself if there's no big commercial interest backing it. The result is that Free Software is often not competitive with proprietary software, except when it does have a big commercial backer (Chromium, AOSP, etc) in which case that developer is often able to maintain a virtual monopoly on patches despite it theoretically being open to competition.