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It's true as far as the editor is concerned, not necessarily what you will get in the standalone due to differences in how they run but should be similar.
Vsync is to limit the frame rate to your monitor refresh rate (not everyone will get 60 but it's the most common by far).
The reason to limit it is so everyone gets the same experience, depending on how things are coded the frame rate can have a massive impact on how the game plays - i.e. someone with a fast computer running at 120fps could get AI running around firing at them 4x as fast as someone running a slow computer at 30fps....
This is why we set minimum requirements - the lowest known set up capable of reaching 60fps.