And to address the confusion over the front desk "closing for the night", I think the OP might have been mis-interpreting part of what I and others said in another recent thread.
First off, as others have said, there is *always* someone at the Front Desk in the WDW resorts.
But what happens is that every night, they must shut down their computer system to run their "end-of-day" processes. It essentially closes the books on one business day, and opens the books on the new one. But it takes a while to process all of the credit card charges, room payments, check-ins, check-outs, and other accounting necessities, and then to open the books on the next day's business.
(Pretty much every retail business in the world has a similar process, but because most businesses aren't 24-hour operations, they're a lot easier to deal with)
During this shut-down, which takes a couple hours, the CMs have very limited access to the system. They cannot print room keys, they cannot check people in and out, they can't even take your money if you wanted to make a payment toward your room charge account.
So, if you arrive late at night (I think they try to get things started between 2 and 3am), you *might* run into the system being shut down to run this process. I ran up against this once where I'd left my room key behind at a bar on PI, realized it on the bus back to the resort, and stopped at the desk to get a new one. But they couldn't make one for me until the morning. They offered to let me into my room using a master key, but my friend still had his room key, so it wasn't necessary.
I don't know for sure, but I would presume that the Front Desk has a procedure in place for Guests that haven't arrived yet when it comes time to shut their system down. (My guess would be they do some kind of basic check-in and pre-print those Guests' room keys and set them aside for when the Guests do arrive.)