It depends on your objective. With culturally linked turned off it may be an advantage/disadvantage depending on what civ you play and who your 'neighbors' will be. Most turn it off because it gets boring to start next to the same civs all the time (If they play the Americans all the time, the will almost always start next to the Iroquis and Aztecs).
If you play the Americans and want as many goody huts as possible, you won't want the Iroquis and Aztecs nearby grabbing all 'your' goody huts (both civs have fast units at the start that will be grabbing goody huts). If I turn culturally start off, I have a better chance of not having these two civs next to me, maybe not in the game at all. I also have a chance of no expansionists being in the game, so I get ALL of the goody huts, getting me out of the ancient era before 2500 B.C.!
You might want to turn it off if you play a civ that would always start next to Greece (hoplites), Persia, Romans or Zulu, for example.
You may want it turned on if you play China, as Japan would be nearby to buy the Wheel from and India to buy Alphabet from.
