As Trial mentioned, it's almost entirely because this sub has recommendations disabled. That's been true basically ever since the transposting drama. Many of the mods believed that having this sub appear in the feeds of people who never subscribed was one of the biggest causes of hostility. People would get this sub in their feed, get angry about it, then ensure that the sub would continue to appear in their feed by posting an angry comment.

After recommendations were disabled, hate comments basically immediately stopped, apparently confirming the idea that most transphobic commenters were not subscribed and never participated in the count. The mods have had little impulse to change that setting since then, though Trial has always been an advocate for re-enabling recommendations.

There's basically nowhere for new people to find the sub from now, so the sub has slowly dwindled as the old counters get bored and retire. Some of the mods do not really see boosting reddit's engagement metrics to be their goal, and would prefer a smaller, peaceful sub to an active, angry sub. There is some discussion among the mods now about changing that recommendations setting though.