Last night I was playing as Siam an Emperor Game, Normal Speed, Large Map, Small Continents 15 Civs (3 more than default).By the end I had 4 cities and another 4 cities. Arabia had swallowed up France, Greece, Germany and Rome and I didn't count but had at least 40 cities. When I mapped out its continent it had only half as many cities and almost a whole era tech lead on me but as it finished off its continent me and my 4 cities over took him in tech. His army was massive but he had no navy and managed to fend him off when he tried to invade me using a mixture of frigates and elephants.
I ended up winning a diplomatic victory and had only 2 more SP to get to unlock Utopia. He had not started the Apollo Program when I won the game. Thats because small cities = more SP = more science AND more gold = even more science. If I can tech 3 eras when someone 5x as large as me can barely tech 2; the OP is simply wrong.
edit: I wasn't even trying to tech hard as I was concentrating on a culture victory and only ended up going for a diplomatic one because it was slightly faster. I had not unlocked any of Rationalism, and if I had I could easily have had another era or two more than him.