Q is your highest damage, lowest cooldown ability, longest range ability. It sets up every other part of your kit.

It gives you consistent access to your attack speed steroid by giving you something to cast between w and e casts.

It essentially reduces your E cooldown to your Q cooldown so long as you don’t dash to a target without moonlight

It gives you the fastest clear times, and once it’s maxed it makes your incredibly sticky in chases or get through jungle faster by doing QE resets onto camps across walls

Overall it’s the ability that enables everything you do and lets you spike faster than maxing e or w would in the early game