Warriors were 21st in midrange shots this season. And all teams prioritize points in the paint, in general. It's not just shooting 3s. The formula is 3s and shots at the rim, and all other shots are supplementary. That's the generic explanation of what analytics are. Essentially, yes, Warriors only shoot 3s is true.
Shooting the 3 is how you beat GS. You don't beat them from the midrange.
The thing that other teams can't replicate is the quality of 3s and overall shots. It's not the shot type, it's the quality of them. That's where GS has the advantage over every team. Rockets, for example, had the right formula, just not the players, style of play and execution to carry it out. As we all know, the defensive attention Steph receives gives his teammates more easy scoring opportunities than any other player. They move the ball better than any other team; they pass the ball turning a good shot opportunity into a great one. If they had a heliocentric offense, and had the same shot type, they wouldn't be as dominant. It's the selflessness of Steph, and the chemistry they've built off moving the ball for the best shot opportunity is why teams can't achieve the same.