"Any competitor service is eventually going to have to age verify users before they access adult content."

Maybe but I just don't see this as a certain thing. The US may implement nation-wide age verification laws someday but it is a long ways from happening. Other discord-like software may be self-hosted by individuals, making enforcing age-verification difficult. There's nothing wrong with this. People would rather have a private place to chat as opposed to a place where your data will be observed by a big company and potentially sold or given to a hostile goverment.