Mr. O'Nolan obviously talks about his specific exp...

# random

[Czar]

Mr. O'Nolan obviously talks about his specific experience (anecdote) but tends to generalize without providing any supporting evidence.
Since we're speculating here, I too will speculate.

I think that the Activity/ComunitySize relationship very much depends on the subject. In Mr. O'Nolan's case the subject is a publishing platform, which obviously attracts publishers/authors same as programming language attracts developers but there similarity ends. There are not many possibilities for speciation (sorry for using a biology term here) with authors in relation to publishing platform.

On the other hand with developers and a programming language there is huge potential for speciation: libraries, frameworks, platforms, programming styles (pure functional, OOP, mixed, scripting), tools, etc. So here I have to agree with @dalexander this speciation allows for tighter interest groups which are subsets of the whole community.

Another point is, all those libraries, frameworks, etc. are created, evolved, revolutionized and sometimes abandoned constantly, so new topics for discussions and new interest groups are also spawned constantly.

I think the problems with slack stem from misunderstanding of its purpose and misuse of its features. Slack is a platform for ephemeral (or semi-permanent if it's not a free instance) discussions, quick questions and answers, but it is not a knowledge gathering or Q/A platform, nither it is a forum. For those types of uses there are other products and Kotlin is represented on them (youtrack, stackoverflow, r/kotlin, discuss.kotlinlang.org) etc.