If it's an excuse to move them off the main search index, why do forums still appear in the main index? They added the tab to give them a boost
in addition to normal search results, not instead of.
Here's what happens when a forum, even in a competitive niche, decides to put in the extra effort:
Build a community and
medium.com
And Google about the topic:
Discussion boards are cool again. Find out why Google now prioritizes them and how to foster community and engagement on your niche website.
searchengineland.com
Recently, we covered some of Google's rationale for ranking forums like Reddit and Quora so well in the Discussion and Forums box for many queries. Just a few days ago, we covered how I was sad to see Google ranking some dangerous and potentially harmful forum threads for health-related queries.
www.seroundtable.com