For larger companies, your community isn’t only on your platform (and it’s never going to be).
Your customers have created their own Facebook groups, subreddits, StackExchange sites, and have built an audience around their own social media channels.
Previous clients have had a policy that varies between legal harassment at worse to lukewarm support at best. Simply ignoring these groups is most common.
May I suggest proactive encouragement?
Encourage people to create their own groups in their city, for their unique interest, and set some loose guidelines for affiliation. Invite these people to submit their group for affiliation with the community. They get promotion and support if they do, but they won’t be legally harassed if they don’t.
Now list and promote these groups on a page in your community. A large number won’t thrive, but that’s true of all groups created. You can filter them out. Now you can focus on the groups which are thriving.
No, you don’t get control. But these group creators don’t want to be controlled.
Instead you get an army of volunteer community managers who can capture great insights, solve member problems, localize/translate your content, and disseminate important information. You might also be building a useful pipeline for future employees.
If encouraging and supporting people to help build your community isn’t a worthwhile part of your job, I’m not sure what is.