Regulation only covers so much
Governing bodies limit driver and ball performance through strict testing, which caps how much distance equipment alone can add. What regulation cannot limit is technique, and modern swings are built deliberately around generating clubhead speed rather than simply making contact, using ground force and rotational sequencing that older instruction rarely emphasised. The equipment ceiling is fixed, but the swing feeding into it keeps improving, and that is where much of the continued gain has come from.
Measurement changed coaching
Launch monitors let a player see exact spin rate, launch angle and ball speed for every shot, turning what used to be trial and error into a precise optimisation problem. A player can now find the specific combination of angle and spin that carries furthest for their own swing speed, rather than copying a generic ideal. That precision, applied across a whole tour, raises the average even before anyone swings noticeably harder.
Bodies built for the swing
Golf-specific physical training, once rare, is now standard at the top level, with players working on rotational power and flexibility the way sprinters train explosiveness. Faster clubhead speed follows fairly directly from that physical development, and it compounds with better technique and better-fitted equipment rather than replacing them. The result is not one cause but three trends reinforcing each other, which is why the increase has proven so difficult to reverse or even fully explain.