They couldn’t have. If they did, then it WOULD be a rehash of the OT.
I’ve got some bad news for you. It was too late. It was already a rehash. The whole ST is just a reboot disguised as a sequel.
And even in TROS, we know the FO isn’t doing so well - it’s what drives Kylo to hog Palpatine’s fleet to make the FO a true Empire.
TRoS is also very vague about the First Order’s level of power and reach. We hear Pryde say that the new fleet will make up for the loss of Starkiller Base, and Kylo makes some vague remark about how the fleet will finally make the FO into an Empire. But again, we never get a sense that the FO is struggling or losing its grip on the Galaxy. That’s just conjecture. We hear a fleeting mention of “free worlds” that will be forced to submit, but we never are shown or told anything about these worlds or their strength or quantity. And besides, during the OT, there existed worlds outside of the Empire’s control as well, but no one would argue that the Empire wasn’t the dominant, reigning power in those films.