He really was just so much more efficient at shooting from beyond the 3 point line it changed the landscape of the game.

If you look at 3pt attempts over time and 3% percentages over time there's a massive spike after Steph. The introduction of analytics plays a small role as well, a lot of shots used to be taken 2'-4' before the 3 pt line it which has largely died (just take a step back and take the 3 for an extra point)

Steph really just showed what's truly possible when shooting from deep and the entire game changes. Growing up playing in Highschool 3s were considered "bad" shots for a lot of players. Nowadays most highschool players are taking 3s and relatively efficiently as well.