essentially their primary purpose is to create a second sub-thread that is invisible to the original thread, thus severing the conversation and damaging the ability for people in the thread to actually engage with each other. this "private sub-thread" mechanic also encourages people to basically just make sub-threads shitting on someone by making it a click away, you don't even need to go through the effort of screencapping someone to shit on them, and even better, it links right to them so anyone who you're asking to go attack them just needs to click a single button to start flaming them instead of needing to type their name into a search bar. awful feature, damages literally every network its been applied to.