vsync is not always the answer, in some games it adds some awful input lag (in many cases solvable with some tweaks, like using fps max 59 or 61), but the worst part is when for some reason your PC can't keep the same performance (16.6MS all the time for every frame) things can get ugly, without vsync with a framerate target this is not really a problem, also, in some games you may want over 30FPS all the time, but your PC is not fast enough for 60, so you can set a limit of 40-50 or something and get a really smooth experience with low input latency,
one game I remember playing, Skyrim, my PC was not good enough at a certain point, without a framerate lock it was a disaster, so much stutter, using a lock at 50FPS made the game completely smooth, also in some games I play there are some areas where without vsync my PC would go over 500FPS, which makes no sense, and in other areas I'm easily into the 40s, so using vsync is not really a great solution, and using a frame rate limit solves the problem.