My latest understanding about the Park Pass system is that there was always intent to keep resort guests separate from AP’s and regular tickets. The decision to separate the other group appeared to be a decision to stop AP’s from eating up all availability for regular ticket guests. The general consensus seems to be that AP’s would not be able to fill the entire park capacity, but they could fill the entire non-resort guest capacity, which would drive away out-of-towners (which is a good thing given current travel safety imo, but I digress).
Also, of note is that (while I’m still double checking this info), it sounds like the “gradually increase capacity” plan has been put on hold due to the spike in cases.
Finally: These parks are at present designed to be uncrowded. We know (and Disney knows) that the parks could handle more at the moment. They plan for them to handle more in the future, but the reality is that they needed a starting point that will generate next to no operational complaints so that policies can be ironed out.