Question: Imagine you are about for one of this peaceful cultural vctory, but then... you find yourself on one continent with 4 other civs (out of 8 total) and there is not much space for you. And your nearest neighbour is a scum like China or Askian. In the same time, on the other side of the globe there is civ which have a whole continet for themself, and is just happy building.
What you gonna do?
Something similar happened to me the other day, Emperor level. I was playing as France, originally planning for a cultural victory. I had good locations for 3 cities only including my capital, bummer. Genghis' capital was 10 hexes east of me, featuring 2 luxuries I didn't have. He had a fearsome army, trying to conquer a CS... but he'd left his capital almost defenseless. I attacked with 7 CB and a couple of melee units, and could quickly conquer his only city before his army came back. I had 4 cities, incuding 2 capitals.
Then, further to the east and not to far : Theodora. With only Constantinople, 2 new luxuries, a couple of wonders, and a very weak army. Oh, my. I captured it as well, of course. Meanwhile, I had time to spot Gandhi, Askia and.. ALEX to the south. Alex! At this point, there was absolutely no way the game was anything else but a domination game. I built a huge military (so did he...), declaring friendship with him, went to war with him against India, and betrayed him soon after (bringing Askia with me). Once Athens was captured and two other cities were razed (one by me, the other by Askia), I easily captured the Songhai capital.
It was like turn 220, and I had discovered the two remaining civs on another continent, Rome and England, fighting and hating each other. I was first in everything although Rome matched my technology. Both London and Rome were coastal, which meant all I had to do was to bombard then capture both capitals with a marine in the same turn. Meh. I didn't bother, as I had won anyway.
tl;dr : sometimes the game definitely messes up with your plans, and you have to adapt. Which is awesome.