You still haven’t figured it out yet? The middle hates echo chambers. The right and left both have echo chambers but they vote against the one that seems more disconnected from reality. By controlling speech and removing content as a knee-jerk reaction to any inconvenient information or opinion as a habit, the left have separated themselves from reality more than the right, by at least a little.
This comes off as threatening to people. Because a mob of people disconnected from reality that will simply silence anyone’s defense of themselves feels like a situation that could get out of hand. And everyone has experienced having their speech controlled. They don’t like it.
All politics is a proxy for culture war. And you lost a culture war by being controlling assholes. Watch you try to silence me right now. Just know that that habit going forward will make you lose more.
The left bans information too. Quite a lot. And actually they didn’t ban books. The government simply did not provide books. You just demonstrated that you are disconnected from reality right then. On every issue the left is disconnected from reality.