Couldn't you use d3 instead vs them?
What, like a peasant? No thank you.
Srsly tho, d3 is i9. It may not seem like a big difference, but in context it makes you the slowest poking character in the game. I’m sure that creates some niche situations where the opponent could out-footsie you where they otherwise couldn’t.
For instance, after Kitana’s B2 you’re looking for the 2nd hit low, but she uses the single hit (-2) and back dashes. Your d1 might catch this, but she could mash her own d3 to low profile and steal a turn, conditioning you to use d3 in the MU.
In the same situation, d3 might be too slow to catch her back dash if SZ hesitates at all. You whiff the d3 and Kitana uses another b2, committing to the full string. She’d punish the whiffed d3 and hit confirm into a full combo.
A 6f d1 gives you some wiggle room to react, where as the 9f d3 you really have to commit to.