Is it really? RMS doesn't appear to have a problem reaching as broad of an audience as is willing to listen to him, and afaik he does not compromise his principles by using non-free software.
The end result is that we are trapped in our own bubbles, preaching to only those who already agree with us. Ideological purity goes on to alienate people. The new generation of computer scientists, developers are not exposed to these ideas, because they are not as accessible. They are using facebook, slack and medium, and we refrain to use those. These are tradeoffs, and clearly, there is needs to be a balance.