Having a tall capital is definitely great but one has to look at the cost of getting one. There are occasions that the capital just can't grow very much (flat tundra start like the recent Rome Deity challenge). Yes you can put caravans on it but a liberty capital doesn't benefit from monarchy. Its better the use the caravans for gold and science and just let cities develop themselves off the land. Guilds should go to the city with highest growth on fresh water. Wide empires already earn more culture than tall ones because of more monuments, culture pantheons and liberty opener so its not as crucial to work the guilds early. I usually time my first couple of great writers for the worlds fair. With 7 or more cities you are guaranteed to win it.
Ahhh ha I suppose I should have clarified what I said, yes you're right you don't need a tall capital although its admittedly better if you can get a tall capital as you have more time to grow and develop it.
Regarding that Rome Deity challenge I must try it out but isn't it better in that circumstance to walk out of the crappy tundra. If it take a few turns to settle somewhere on a hill adjacent to a few nearby bonus tiles the benefit to early growth and production will make those hammers and your civ will be better in the long run.