Okay, this is gonna sound really mean, so please don’t take this the wrong way:
She’s not. If she is, you’re playing her wrong or you’re getting zoned hard, meaning you need to be playing more conservatively.
Quinn is heavily reliant on consistently hitting her Harrier marks. While it’s true that your Q and E do provide Harrier marks on hit, you should be relying heavily on your passive for those marks and using Q and E situationally.
As an example, I go Q, W, E for lvls 1-3, but I personally max W first. There’s a few reasons for that:
1.) Even without crit, you get your passive frequently enough that you don’t have to rely on manually placing it with Q and E.
2.) You should be itemizing for issues you’re facing in lane. Take Shiv for wave clear if he enemy is pushing hard instead of relying on Q, which does gobble up mana. Additionally, Essence Reaver is a personal favorite of mine on her when going full crit, since it cures her mana problems more or less.
3.) Maxing W gives you substantial short term increases in movement and attack speed. This increases your DPS and kiting potential against certain champions.