The point is that there is no Disney park here so the ship is the park essentially.
I think we all understand the idea, but pitching Pym Quantum Racers as some sort of equivalent to a land-based theme park ride is really dishonest. Singapore already has a great Universal theme park. Disney's market theory here is frankly wrong and as soon as excitement fades over this ship they're going to take massive price cuts and have trouble filling the ship.
I'm not a hater of the ship, it's just that Disney insists on cramming their specific style into the industry in a way that hasn't worked for anyone else. Majority of the industry doesn't do just 3- and 4-night sailings, and they sure as heck don't do port-less sailings. They don't have the hubris to think that everyone else is wrong about what the consumer has said they like over the course of decades.
The bigger issue in all of this is that Disney doesn't want to take families to Pa Tong because it's not seen as family-friendly, and other ports like Malacca and Klang maybe aren't ready for the primetime with a giant 200k+ GT ship and 8,000 passengers. There's just not a lot of places nearby that the typical Disney family would find picturesque enough or that feel safe enough TBH. And some of these ports in that area are really far! Disney would likely need to offer 8-night sailings to reach some of the ports in Vietnam. And lol, they'll never do that, because Disney knows best and Disney knows that customers would never book an 8-nighter when a 3-nighter would do the trick!
So all of this is to say that Disney intentionally narrows their market by insisting on short sailings, by insisting on not visiting ports, and they're going to find that by limiting the size of their market so far, they will have trouble filling such a large ship. Remember, Singapore only has something like 73,000 hotel rooms. And the
Disney Adventure has 2,100 staterooms. The Adventure now comprises something like 3% of all hotel capacity in the entire country!