There is no reason you cannot design a rail based system (light-rail, monorail, etc.) at a reasonable construction cost which operates on a point-to-point basis. It would be more efficient than a "hub & spoke" layout, but more importantly, it has long been demonstrated that people do not like to change trains (or buses or airplanes), even between modes. Passengers want a one-seat ride from origin to destination.
Rail does not require hubs any more than buses do.
Infrastructure does matter, however, when it is "on-stage" or otherwise part of the "show", which by definition would include transportation within Walt Disney World. The dumpsters aren't placed out in plain view (doesn't mean you can't ever catch sight of one, of course); When trash receptacles have been on-stage, such as trash cans in the parks, they have (generally) been themed or at least distinctively presented. There are whole threads around here devoted to well themed restrooms, while even parking lots are at least landscaped - no plain, ugly asphalt jungles. Point is, the presentation of infrastructure within a resort district does indeed matter.
The one way to get more people out of their cars and into mass transit is to make the transit option more convenient than driving. We all know the drawbacks and delays inherent in Disney bus transportation - they aren't more convenient, and thus people drive.
Science is hardly always true, unless you believe that the Earth has aged 2 billion years in roughly the same amount of time that Walt Disney World has existed. Science is always developing and knowledge expanding, and what was once thought to be true is revealed to be incorrect. Believing in science (sometimes to avoid belief in something else) doesn't make it true any more than believing in the tooth fairy makes her real.
Expanded road capacity is not necessarily the same thing as reduced congestion.
@lazyboy97o is correct; Studies have shown that roads tend to reach capacity soon after they're expanded. You cannot solve transportation issues solely by building more lanes/roads. There are limits to how much you can do, and literally how wide you want (or are able) to build a highway. Hence, the push for greater rail-based options across the nation (but they don't come cheap).
Rails are actually the modes greatest asset, not a liability (dedicated right-of-way, instead of mixed with congested road traffic).
A loop would be silly and a hub - again - far less efficient than just running the trains (of whatever type) directly to the destination. Fortunately, Walt Disney World has a relatively limited number of origins (resorts) and destinations (parks and Disney Springs) as opposed to literally thousands for a major city (bus stops every couple blocks, for instance, on miles of route). Things are far more manageable.
And to a much greater degree, arguably, than the entire NGE debacle. Perhaps for less cost, too, depending on whose numbers you use.