I don't think the goal is to predict crowds, but to manipulate them.Disney Parks' data gathering and parsing was world class long before park reservations ever became a thing. Despite the hell given to 'Disney IT' (myself included at times) for their forward facing systems (not maintained domestically for the most part, BTW), the backend stuff is renowned in the IT world for being some of the best designs and working systems in the world, despite what some here may choose to believe.
All of that to say this. Disney does NOT need the park reservation system to gauge staffing needs in the parks. I'm not really sure I remember if that angle originated on the boards, or as a 'by the way' comment from some Disney propaganda along the way, but it is nowhere near essential or necessary to predictive park staffing.
Disney Parks' data parsing can tell you when a purple polka-dotted magic band is going to go thru the 2nd turnstile at Epcot International Gateway after 11:07 within seconds. They know exactly how many people they need for the Magic Carpets of Aladdin at 3:04pm as well. And at 8:00am also. It's that good. I'm not exaggerating. Please consider stopping the pass we are giving them on the necessity of 'park reservations' for staffing predictions. It is totally and utterly ridiculous.
Let's say they predict that MK will have 80k visitors one day and AK 10k. I might be exaggerating, but there are times, like some holidays and non party days when demand for MK is much higher.
With those numbers they need full staff at MK with extra people just to handle the crowds and people would be miserable and probably spend less due to lines for everything, from attractions to shops and restaurants.
In the meantime at AK the few people there will have a great time but Disney would not be able to avoid staffing all positions (Safari can reduce the number of vehicles, but Everest has just one loading platform, that has to be staffed anyway).
But now they can artificially cap MK at 50k. Those 30k people who would have gone to MK have to chose another park or not go at all. If 10k go to each one of the other parks it's a huge victory for Disney. 20k people at AK is a more reasonable number and people at MK have a better experience, and crucially, they'll spend more money.
Park reservations will go away only if too many of those 30k decide not to go at all, causing a loss of revenue. Since we still have park reservations, it seems it's not happening (unfortunately).