Before the advent of FP+, one of DHS's many problems was that guests would flood it in the morning hoping to get good FP return times.
With FP+, the return time has been selected by the guest. Even if many don't like it, guests will grab the 9-10 PM FP+ for TSM because that's the only thing left. As corporate Disney wants, those guests will plan their days around it. Maybe go to another park. Maybe sleep in. Maybe shop at DTD. Maybe hang out at the pool. The point is, rather than racing to the park in the morning with everyone else, those guests will plan on being at DHS later.
Unlike FP, FP+ return times start right from opening. That sucks because Standby lines will grow longer earlier. As a results, there will be less advantage to being at any WDW theme park for opening.
Between guests planning for late FP+ return times and guests having less of an advantage being there for rope drop, FP+ might more evenly distribute WDW's crowds throughout the day.
What Disney executives want onsite (especially Deluxe Resort) guests to start thinking is: "Morning, noon, or night; Standby lines suck. The only way to avoid them is to stay onsite longer to get more FP+ selections."
It's their dream. It's our nightmare.