Earlier quoted context omitted.
This is a little bit different. The only reason proprietary software exists is the copyright clause in the Constitution, which grants the government a right to issue limited-time monopolies to creators of original works. Revoking a government-granted monopoly is very libertarian. Revoking mutual consent is the opposite.
Proprietary software would also exist without any copyright, people would just guard their trade secrets, obfuscate code and put it server-side more than they already do now. The free software movement uses copyright to protect the freedoms, it is not a "libertarian" movement and never claimed to be. It wants to ensure that programmers and users of software have the four freedoms that RMS has laid out in many talks.…
The reasons one sometimes has to use GPL software are quite similar for the reasons one sometimes has to use proprietary software. So the answer for GPL haters should rather be: avoid using GPL software (if possible), but more importantly: don't contribute to GPL software and contribute to software with "better" licensing so that one can (in future) create devices that are proprietary-software-free and copyleft-free at the same time.