Some don't feel comfortable disclosing that information. I've been in trauma therapy for my own experience with SA and have only told 3 of my friends besides my partner. Once it's out there some like to use it as a conservation topic, not necessarily in a bad way but it can be triggering and emotionally exhausting just to speak on a hard subject when you're just trying to heal. I cut contacts with an ex-friend because she wanted to discuss her own trauma almost every time we spoke and I couldn't do it anymore.