While this is 100% correct that Surveillance-resistant systems or other technical means are not he answer to authoritarianism, this statement has at least two problems.
1. A technical solution may not in itself be the way to counter authoritarianism, but may assist in either resisting it or prevent it from gaining enough power. Since democracy is a state of permanent fight against the iron law of oligarchy (which ultimately leads to authoritarianism), any thing that reduces the power of the govt to a certain extent is good. In other words, we don't want the govt to be 100% efficient in whatever it does. Arguably modern tech in current state gives the govt near 100% efficiency in surveillance, so this has to be countered with any means, most of which are of course political and legislative, but surveillance-resistant technology can also play its part.
2. Authoritarianism is not the only threat. It's entirely possible to have a democracy in place and yet have a miserable existence under it. For example, if every perfectly democratic law we have now is enforced with 100% efficiency it will feel very close to a dystopia. Technology can help alleviate this to a certain extent.