A successful outcome depends on the type of forum.
I’ve joined many forums that are transactional based. I joined the UPS forum to try and find out why my package was delayed. Once I got an answer, I did not feel a need to return but I had a successful outcome in that I got the information I wanted and my faith in the UPS brand remained mostly positive.
Other forums take you on a journey but only for a short part of your life. When I was researched electric vehicles, I joined a few forums to chat to owners of different models, and when I settled on a Tesla, I joined a forum to discuss that car in more detail and what the delivery experience was like as well as get help with picking a home charger, etc. Now that I have the car, I do not need to contribute as much and I drop in less frequently but on the upside, I help others now I have some experience with the car, so the loop continues.
I would also add a successful forum for us helps the entire team keep close to our customer base. Rather than having siloed customer support channels, that are typically only seen by customer support, the forum opens the voice of the customer to the public, which means every team member can take time to check in and see what our customers are asking about, struggling with, excited for, requesting, showing off and more.
This list looks amazing. Can we do a poll to learn the rank of importance for these goals from community builders? I am often under the impression that SEO is the only reason a lot of communities have to build forum. But, I feel I might be wrong.