A few things to share and suggest:

Disclosure, my perspective is that of a frequent lurker on the Java and c++ forums.

It's a good thing to try and improve the rules, so kudos for trying this, but let's also be pragmatic and "careful what we wish for."

Your original history, suggests that the initial site policy was not wrong, or initially inadequate; it observes that : a) it did not scale when the community ceased to be the original group with existing relationships. b) the attempts to tweak it were largely overwhelmed by the effects of massive growth.

Perhaps there is (in reality) no adequate solution for larger scales, that does not impose so many restrictions that it must also destroy the primary benefits. Just because we want there to be an answer to a question, does not mean the solution exists. Example of such a fallacy: What is the programs/projects % complete? See CM*

So, rather than seek a "one size fits all scales" policy, perhaps a solution is to allow the self-formation of smaller communities, wherein the growth of real (as opposed to "'virtual") relationships can form. Where new seekers after knowledge, can find a path to the community that best matches their needs, level of understanding, and encourages actual relationships.

Humans, being what we are ( ignoring the politically correct euphemisms and wishful thinking for just a moment ), treat others with the level of effort, respect, and encouragement we each think the others own efforts deserve. Our gifts, (in the form of responses to questions) are directly proportional to that implicit assessment, YMMV.

Given that trust and respect must be earned, which may take a long time, it follows that any such community will need time and opportunity to get to know one another.

Communities with civility and trust may form much more quickly, and effectively, when the qualities can be attached to a real person, someone to care about, rather than an abstract handle, chosen on a whim. My nom-de-plume, for instance, is ShinyPixel, a common and annoying defect in a digital display, who could love that?

Suggestion: Encourage and enable small groups, (like the original community) with shared backgrounds and interests, and allow them to moderate in/out others that meet their criteria. Sure, maintain some generic and over-arching levels of legality, decency, neutrality and all the many other (insert the latest zeitgeist)'ys you need. But don't expect them to be identical in all ways, permit a diversity of each community and promote shared trust and civility.

Technically, and speaking only about my preferences, most of the answers focus too much on competing for syntax and expressions in code, rather than the underlying Idioms, an unofficial online "debug to correctness race", kicked off by each posted question.

The idioms, algorithm, and concepts the questioner generally needs to learn, to find a pragmatic solution to their problem may be omitted or unstated. The result is a stream of random code suggestions get posted, for people who haven't done their homework, which is, IMHO, unproductive and wastes the good will of contributors. See JB* Foreword, for a much more perspicuous definition of "customary and effective usage."

Finally, and then I will return to lurking: may I respectfully suggest checking out Confident pluralism, by John D. Inazu, 2016. A recent and highly readable tome that addresses the topic of "Surviving and Thriving through Deep Difference" JI*

Best wishes to all, and thanks for the many answers, past, present, and future.

ShinyPixel.

References: JB* Effective Java Third Edition. Joshua Bloch. 2018 CM* Extraordinary popular delusions and the Madness of crowds. Charles Mackay LL.D. 1852 JI* Confident Pluralism. John D. Inazu. 2016