The Opera forums weren't shut down. They were moved to a new location. The chat still exists as well.
The My Opera site was what made people love Opera? Uh... No. Opera 12 had tens of millions of users, and hardly a fraction of those visited that site.
The "Opera community" is, or was, a thing. Opera spent years cultivating an actual community around their users, with forums and chat and social networking features galore. Then they shut it down last year.
The Vivaldi folks have also started Vivaldi.net, which appears to be an attempt to keep that community going elsewhere now that Opera has essentially axed everything that made people love them in favor of being an also-ran Chromium fork.