He also has the gravity advantage. Steph gets doubled from 35 feet basically every time he runs a PnR and causes chaos when he's off-ball running of screens. Gravity's become a meme on this sub but it's a really big part of Steph's value, it's the reason there's such a huge discrepancy in his on/off numbers vs his 3 all star teammates (and everyone else on GSW).
on/off 2018:
Curry: +11.8
Durant: +2.9
Green: +2.1
Klay: +5.7
on/off 2016-17 regular season:
Curry: +17.5
KD: +8.2
Green: +11.5
Klay: +7.9
on/off 2016-17 playoffs:
Curry: +20.6
KD: +6.0
Green: +18.9 (shared the majority of his minutes with Steph)
Klay: +6.0
https://www.basketball-reference.com/teams/GSW/2017/on-off/ https://www.basketball-reference.com/teams/GSW/2018/on-off/