I personally tell people when I want my threads to stay on topic. for example I started a thread in self injury in which the focus of the thread was positive ways to check in with each other and positive resourses and ways to help others in stopping their cutting and other self injury behaviours. I let it be known that that thread I wanted it to remain focused on the positive so that those looking for positive ways to help themselves they did not have to read through some possible negative rants and cutting activity that could trigger the person that was already on rocky ground when they went looking for that thread. When some expressed the need to also be able to vent about their cutting behaviour and the things that triggered them into cutting I started another thread one specifically for that so that those that wanted a place on my threads to vent and talk about the cutting and that way those that wanted to be able to read only the positives still had the thread that focuses on the positives free from the graphics of the act of cutting and rants and so forth.

Also there is nothing here that says you can't start your own thread that is a thread specifically for tangents and multiple topics