Wow! Thanks for sharing your story. I guess this is a reminder that every community is unuqie and deals with its own set of circumstances that require different strategies and efforts. Sorry it didn’t work out for you this time!
I have found that Discourse works really well when you are starting up a new community or when there is a high incentive for enough people to participate to get the ball rolling on the forum. With enough people actually logging in to participate - some people will always be recalcitrant but we can pull them along thanks to the email notifications. I recently migrated a yahoo group and it took months before it started to look successful. I was constantly cherry picking people who were leaders in various ways to come and start topics and get things in the community going via the forum. You have to be dogged! 
And then, yeah, sometimes you have to admin defeat. 