Yes, Usopp should have beaten him even if he needed some help.
Remember when he used to have dials? Do something like him luring Ulti in attacking him with one her strongest moves, putting it into a dial and then redirecting it to beat Page One and fuck himself up at the same time.
Or stick them both in a room and have Page One beat the shit out of Usopp while Ussop’s running around, looks like aimlessly, then he uses a smokescreen, darts out of the room, reveals he’s been planting some plant landmines then snipes one to set them off, blow up the room and beat him.
Or have him lure Page One to the edge of the cliff and use some plant sniping to launch him off the island
Or just give Page One some sort of weakness to exploit.
All these sort of things are how Usopp should and has won most of his fights, he doesn’t take people on face to face. He wins using creativity and tricks. What Oda did was just lazy.