my understanding is that where numbers have been not allowed on here is because posting numbers can cause others more harm...

not everyone goes through this kind of thinking pattern but many people with weight problems, OCD or other mental disorders do go into this kind of obsessive thought process around numbers, it could be about weight, or any other number reference...

this is a mental health website so its most likely geared for not causing members more harm than good. so there has to be rules and guidelines to prevent as much triggering of members mental disorders as possible and one way to do that is by limiting /not allowing discussions on topics like posting numbers, or most common triggering words, or topics that cause problems with people of mental disorders.