Many comments here have taken the First Order superiority so far to be that they are in charge. There is no evidence of that.
“The FIRST ORDER reigns. Having decimated the peaceful Republic, Supreme Leader Snoke now deploys his merciless legions to seize military control of the galaxy.”
Reign:
a : royal authority : sovereigntyb : the dominion, sway, or influence of one resembling a monarch
Read what you posted. The quote from the crawl? It doesn’t mean that the First Order has taken control of any planets. It means they were victorious in the last movie. How much time has passed? Days. The First Order found out where the Resistance base was and are now moving in to wipe it out. That means very little time has passed. The Resistance has a few ships and has nearly finished the evacuation by the time the First Order arrives. No time at all. No time for Snoke’s forces to achieve any great victories or subjugate any planet. The text you posted says “now deploys” - present tense. That means it is happening, not has happened. Reigns is a bit strong for the situation that the rest of the crawl then describes. Typical of a SW crawl.
So, to resummaraize, the First Order destroyed the Republic capitol and fleet in the Hosnian system. They have regrouped after the destruction of Starkiller base (which wiped out a chuck of their power) and are attacking the Resistance base and Snoke has ordered his legions to go seize control of the galaxy. Nothing is done yet. It is in progress. That also explains why no one answers Leia’s call. They are set to defend themselves from Snoke and the First Order. Snoke and the First Order have not yet won. They have only won the first salvo.
I hate to bring in the PT, but the Clone War showed how hard it is too take a planet so nothing is going to happen overnight. You are reading too much into the word Reigns without paying attention to what the rest of it says.
Episode VIII
The Last Jedi
The FIRST ORDER reigns.
Having decimated the peaceful
Republic, Supreme Leader Snoke
now deployes his merciless
legions to seize military
control of the galaxy.
Only General Leia Organa’s
band of RESISTANCE fighters
stand against the rising
tyranny, certain that Jedi
Master Luke Skywalker will
return and restore a spark of
hope to the fight
But the Resistance has been
exposed. As the First Order
speeds toward the rebel base,
the brave heroes mount a
desperate escape…
The timeing and the second paragraph of the crawl refute your claim that the First Order has already won, as does the lack of help Leia receives when she send out the call for help. You won’t get help from people who are preparing for an attack. And the results of the film call back to this in that what Luke does on Crait is that he definitely restores a spark of hope to the fight and that final scene with the stable boys proves it. It is not a done deal yet. The fight is not over. Leia and the Resistance stand in the way and they First Order couldn’t even manage to wipe them out. Very pad PR for the First Order. Not what you want to have happen when you are trying to take over the galaxy. Oops.