Being tall (longer lever) or built like a lineback (more mass) can both be big factors, on their own, or in combination.
And flexibility matters (extending the swing raduis to the feet)
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Evan(Big Cat) Williams is an example of a player with both factors you speak of. He is something like 6'6" and probably over 200 lbs.. He was a former National Long Drive Champion.
Now there are guys like Chi Chi Rodriguez, Charles Howell III, and Ben Hogan... all small, light guys. Ben Hogan could drive the ball long when he wanted to.
Technique only gets you so far when you find your maximum hand speed. Once you tap that out, only thing left to do is to get the extra distance through stronger muscles and working out.
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I'm not a TGM or PGA certified Pro, but I did stay at a Holiday Inn Express last night