Sleeping and being awake at rest are almost identical in terms of calorie
burn.

Your weight will end up higher at any time of day, not just in the morning
after sleeping, assuming that you eat more than you burn.

Small intakes of carbohydrates may never be turned to fat; they end up as
glycogen stores and are recoverted to glucose as needed.  This is true up to
about a day's worth of calories, spread over the day.

"An ounce of prevention is worth a pound of cure".  This could be
viewed as another way to phrase discipline or not depending on
your view.  In the prevention view, eating a good breakfast prevents
hunger for much of the rest of the day so it makes it easier to not
overeat.

I suspect that "not eating after 7PM" tends to mean eating the
same as before until 7PM and then deleting any evening snacking.
If so then it's easy to figure out why it works - It's less total
eaten
at a time that will have little effect on your total hunger for the
day.

ANYTHING, as far as I'm concerned.

Things like not eating after 7, eating breakfast, etc., are not
necessarily the CAUSE of maintenance, they're just empirically
associated with people who maintain.  I'm sure there are people who
follow all the "rules" and still gain weight back, or people who do
whatever they want, and keep the weight off for the rest of their
lives.

In the end, it's really up to you to WANT to keep the weight off, and
take steps to correct any undue weight gain that occurs during
maintenance.  Everything else is just personal preference and
"tricks."

Still, I do feel better when I eat breakfast (even just a bagel and
cream cheese, and a cup or two of piping hot black coffee).  It
doesn't fill me up, but I'm not hungry until lunchtime.  And because
I've already "spent" some calories, I can actively plan out my next
meals for that day, with specific calorie values in mind.

As a college student, though, I regularly eat after 7PM.  Particularly
when my job keeps me at work until thereabouts (IT work is easier with
no users logged on), and I don't get a chance to grab dinner.  Over
the course of 24 hours, I'm still eating the same number of calories,
and over the course of a week, I'm still coming up short, and I'm
still losing weight.  As long as any changes I make are very stable
and I incorporate them into my routine (ie. a yogurt EVERY NIGHT at
around 9pm), I find the effect disappears over time.

In the end, little tips and tricks like not eating after 7 are only a
means to an end.  They're just tools that help a majority (particular
those 9-5ers who eat dinner at roughly 6-ish, and maybe are tempted to
munch on an excess bag of chips or a bowl of icecream afterward,
having already used up their daily calorie allotment), and do much
less for others.  It's all just preference.

I won't really contest that (especially with an "almost" qualifier),
but do you have any respectable data on it?  I've only ever seen
"expert" answers and the like online, but it never bothered me enough
to dig deep into medical journals, etc.

As Msxmaniac said, and as most faux dieters would rather ignore,
"It's the total number of calories that you eat and burn that matters,
not specific [habits] or foods."