At the risk of being wrong, I'd even go so far as to say they need this software.
But does Stallman ever need to use software written by Zuckerberg or Facebook employees?
Personalities and errors in judgment aside, give respect and credit where it is due.
I have never needed Facebook's software. And I doubt I ever will.
From a purely utilitarian viewpoint, my gratitude goes to Stallman and the people who brought us the internet. I'm not sure what I could thank Facebook for.
If Zuckerberg had failed to be in the right place at the right time, there would always be a substitute.
But if there was no Stallman back in the 70's and 80's, would we still have gcc, gdb and so much free, open source software?