"people who don’t have kids (aka me) aren’t allowed to respond or use the forum"
This isn't the case. There are plenty of discussions that don't involve kids at all. I don't tend to engage with the kids posts a lot because, despite having a child who I believe is autistic, many of the challenges posted about are not ones faced by my child. Some people do post a question and disappear but I see that as just desperately seeking help so if there is anything I can say that might help them, it doesn't really worry me if they respond or not. They might have read it and found something useful and that's enough.
I’m trying not to engage much with the parents as well, unless their situation is very similar to mine (ex. if they’re Autistic with an Autistic child). Reason being, just as you said, they tend not to stick around. It feels like most of them are here not to get advice, but rather just to complain about their circumstances.
I have used PMs a lot with other people on the site, typically for subjects they don't want to discuss publically, either for the sensitivity element or because they fear judgement from some people on the forum.
I believe you need to make a friend request to the person you want to DM and have them accept it before you can communicate though. It is a bit more restrictive than many other sites.
There was also a lot of fuss over the fact that PMs are not strictly private (ie some mods have the ability to access them) which caused a number of people to leave the site at the time. I think this put a lot of people off using them after that.
