I'm not sure there's any advantage to having a 'private' discussion of such matters.
The first objections are ones of principle ... free speach, the open discussion of ideas, etc.
The very idea of a 'private' forum feeds every assertion of collusion, paranoia, and distrust there is out there. While I can't speak for others, my 'business model' is totally dependent on the trust my customers have in mt.
In a practical manner, anyone can be anything on the internet. It wasn't so long ago, on this very forum, that a 'multi million dollar a year contractor' was exposed as a paycheck collector, with a revoked license. Oops. That didn't stop that gent from asserting all manner of business expertise.
We also had another guy, a few years back, asserting to have great legal expertise .... while also advocating patently illegal practices.
So what of the new guy, wanting to learn the ropes? This is precisely the guy who would be excluded from the forum.
Finally, I question the value of keeping such discussions away from the eyes of customers. IMO, there's just too much 'confidentiality.' I suspect that a lot of consumer complaints would have been avoided, and hack work prevented, if only the consumer had the facts available, had some appreciation of how a business operates.