Yep, that's the issue. Chastity is the one thing we know we have in common, and the one thing we know we'd have in common with the hypothetical new woman logging on to find out what this new fetish of her husband/boyfriend is all about. But chastity is, as Tom articulated years and years ago, mostly about nothing happening.
"Hey Bob, how you doing?"
"Great Fred. And you?"
"Good. Your KH unlock you today?"
"Nope!"
"Neither did mine!"
... pause ...
"Okay, well, see you tomorrow."
"See you tomorrow."
Aside from occasional discussions about a new device, or mechanical issues with something, there's not much titilating (so to speak) to discuss about Chastity.
So any sort of long term sexually arousing engagement from men is going to drift to the other kinks, where active stuff can happen on a regular basis while the cage stays locked. And men looking for a mechanical or practical discussion are likely doing that most often on a forum about building RC cars or model trains or backyard greenhosues or getting the perfect smoke ring on a brisket. This place is primarily a sexual interest forum. If the site itself stops being that, it will stop being period. So there will inevitably be discussions about all sorts of more-than-just-Chastity topics, many - or most - of which will be off-putting to Mrs Noob. In time she might grow to like some of it, but starting off?
Imagine a woman making her first foray into a sex shop to buy a vibrator. But the vibrators are all the way at the back and to get to them, she has to walk past live demonstrations of CBT, scat play, pegging, overweight guys in French Maid outfits with some woman screaming at them that they're worthless worms... I don't think she's going to make it to the vibrators.
I don't think there's a viable way to turn this site into a "Safe Space for Noob Keyholders." It is what it is, appreciate it for that. Trying to make it something else is like moving to the quaint, bucolic village for the wonderful small town vibe and saying "You know what this place needs? A Starbucks. And a Planet Fitness. Maybe we can get a Trader Joes..."