I’ve experienced this. If you are downvoted in quick succession you will get a “you are posting too quickly” error if you try to reply to anything… even if you didn’t post anything except the original post. Seems to last about a day.
I think most people who have the technical skill to do this effectively don't telegraph their intentions on what is, to all intents and purposes, social media.
But saying people don't broadcast their criminal intentions on social media... I'm sure that's more common than you think :P