Without a doubt, the Rockets certainly popularized the heliocentric offense by using 3-pt spacing, but what I'm arguing is, when we were all talking about how the NBA changed, in real time, we all had Steph at the center of that discourse. He was the star of that show. He made everyone tune in to a new brand of play, which the Rockets didn't do. I understand the point of arguing about how the Rockets led a specific type of play around 3-pt shooting, but the 3-pt era isn't limited to just being that.
Changing the NBA is how folks see it and how they discuss it, after all, it's sports, and not something which is theoretically judged by some numbers off a stat sheet.
By in large, when the NBA has ushered in a new era thoroughout history, it's coincided with someone being the face of that, where they might not literally be the source of every change, they're just the frontman of it, and to me, that's Steph for the 3-pt era. Years from now, this period will be remembered for his 3-pt shooting and not the Rockets'.
That's just how I see it.