The point is... its more than 'your money' that counts. The more often an AP goes... the lower the return for Disney Verse a fresh visitor each time.
APs are more loyal, and will do things like spend more, buy collectibles, etc... but in the grand scheme of things... the big money comes in the volume of 'people having their blowout vacation' and splurging because they are on vacation. The repeat visitor doesn't splurge like it's their only chance to be there...
This is why the repeat visitors are good for filler - they are easier and cheaper to attract back - but you're not going to get a 'once in a lifetime' spend out of an AP each trip. While fresh meat will spend like that.. and they don't need to do it multiple times, because they get more fresh meat tomorrow...
I don't think this is true.
Most one-timers don't binge-spend when they go to WDW; most try to do WDW as inexpensively as possible. They stay offsite, or MAYBE at a WDW value resort. They scoff at the idea of spending $800/night on a hotel room, or $50 on breakfast. They only plan to go once, so they see no reason to invest heavily in Disney paraphernalia.
The people who are buying Dooney and Bourke pocketbooks and collecting crystal castles are are the folks who REALLY love everything DISNEY! They go once a year or so, so they KNOW the culture of WDW. Mostly, the people dressing their daughters in princess gowns are doing so because they know that is a THING at WDW. People look into buying AP only AFTER they are addicted to frequent returns. AP's are how they rationalize their addiction.
I have bene a forum member for quite some time, and answered many first-timers' questions. A few plan character meals every day, but most want to keep trip costs as low as possible.
Repeat visitors on the other hand, remember the excitement of their first trip, and they want to experience that same high again. So they buy an AP...and keep upgrading their way to "new" experiences. Maybe if they have the newest lightsaber, and wear the newest Cherry Lane Dress while eating at Cali Grill it will be as thrilling as their first trip down Splash Mountain!
As for how that is relevant to FP+, I'm not 100% sure. Some first timers know to use FP, some don't. I suspect though, when things like 9/11, the economic crash, and the pandemic hit- and one-timer people are scared to travel, WDW is glad local AP holders keep coming. I've watched this boom/bust cycle for some time, not just WDW. People's willingness to travel is fickle.