That's exactly the argument. Folks who are on the fence about seeing a movie but don't have the time and decide to go and see it on Blu Ray/Streaming/Cable later now have the time off in the holidays to catch a movie.
Mind, I'm not completely convinced by the argument myself. But that's more or less it in a nutshell.
---
The analogy I made is that if there is a theoretical celling to a movie, releasing it in March you might get 50 to 70 percent of the total, in summer 70 to 80 percent and in the holidays 80 to 90. Maybe. Possibly.
That's the theory anyway and is one way to explain why some movies tend to do better than others at various point in the year.
As to why movie studios hadn't released blockbusters here? Perhaps it's because Hollywood can be EXTREMELY conservative at times. They refused to release blockbusters outside the traditional summer months until other films proved you could get massive bucks elsewhere in the calendar. February was once seen as a dump month, but Deadpool (and to a degree 50 Shades) shattered that notion. So too for other months.
A different way to put it is: No one likes to be the first to stick their head out of the trenches. Well, TFA did it by necessity and while it didn't get a multiplier many holiday movies got, it still cleaned up in the weekdays FAR more than it would have done in any period, including the Summer.
====
As I said, I'm actually something of a multiplier skeptic when it comes to the holidays, so I know where your coming from. But it's undeniable that there is more time off to see movies in this compressed frame, and movies have historically taken advantage of it. Just not blockbusters for whatever reason.