I don't disagree with your point, there's quite a bit of knowledge around building communities and moderation that's been around and honed for at least a generation. And we should take that knowledge and build on and around it.
That said, folks have been going on about "Eternal September" for decades. Granted, people are born all the time, but they've grown up in the age of the Internet.
As such, it seems to me that at some point (if not now, when?) we need to get away from that particular excuse.
Anyone born before the Internet (myself included) has had a long time to figure things out, and anyone born in the Internet's wake is immersed in it from a fairly young age.
So why do we continue to use "Eternal September" as a foil?
It's entirely possible I'm missing something important, and if I am, please do enlighten me. Thanks!