Answer:
Rome was able to gain its empire in large part by extending some form of citizenship to many of the people it conquered. Military expansion drove economic development, bringing enslaved people and loot back to Rome, which in turn transformed the city of Rome and Roman culture.
It failed because China is a land of the proletariat and the ruling party is a communist one while the fifth modernization was about introducing democracy. Since the party represents the working class and the will of the people in theory, democracy is against it since it would enable those who are against the party to also compete which would in theory mean that they are against the people.
