Actually, that's not "all we know." We also know that, per the disney website: "During the limited capacity period, it may be difficult for Annual Passholders to get park reservations to visit on certain dates. To help manage capacity, total reservation days held at one time will be limited." They don't say total reservations will be limited unless you have a resort reservation. They could have said that, but they didn't.
Anyway, as a lawyer, I kind of take umbrage at the notion that just because is "legalese" it is not true. Disney's lawyers may have advisedthem to put that language that resort reservations do not guarantee access in there, but if they did, it's because they view it as something that is important. Lawyers don't require that companies prominently warn against every risk, no matter how unlikely--sure you may see risks of remote things like hurricanes and terrorist attacks in the "fine print"--but they wouldn't prominently put the "no guarantees" language in the few bullet points on the resort reservation page unless they thought it was a risk that was likely to manifest.