You're conflating two different issues. Some of the specific, concrete planning of violence may have taken place on Facebook. That doesn't appear to have been

You're conflating two different issues. Some of the specific, concrete planning of violence may have taken place on Facebook. That doesn't appear to have been taking place as much on Parler -- possibly because it was less private -- but there was plenty of generally violent rhetoric on Parler, just less specific. "We should kill this person" (Parler) versus "Let's all meet up with our guns here" (Facebook).