I do not recall how long I have been playing WoW. I received an invite from someone long ago and have been playing since sometime during beta. I arrived in the forums, during July 2019. At that time I encountered an issue with which help and support refused to assist. Instead they directed me here to the forums. Interestingly, at that time there was also a forum link within the app. This made the forums easily accessible to all players.
As you noted many of the early forum posters are no longer present. Unfortunately many early adopters left during Ludia’s early struggles (which remain unsolved) with PvP matchmaking and ToM. At this point I suspect there are maybe a couple hundred beta players active. Perhaps there are more but those I knew have left.
Additionally, the spirit of the forums turned dramatically negative since the introduction of ToM. I doubt they wanted newbies to be readily introduced to the rampant complaints. issues and concerns shared in the forums. This could explain why the link was removed from the app.