Why is .Touched discouraged for hitboxes?

I was passing by some posts related to making hitboxes. I noticed often they discourage the use of .Touched. I would like to understand the reasoning behind it.

Because the hit detection is not as good as when using RayCasting/FastCast/ClientCast. And it can be laggy.

What exactly is not as good? (char limit)

The hit detection when using Touched can be incorrect/not so precise and out of sync. If you have a sword fight and the other player’s ping is bad then they will lag causing you to miss. That won’t happen when using ClientCast: ClientCast - A Client-based, Idiosyncratic Hitbox System!

Is it any different from using :GetTouchingParts()?

Unfortunetly, I cannot afford to use this one given I want to make this hitbox be AoE.

Yes. If you were to loop the GetTouchingParts it would cause lag.

But would, in return, have better performance in shorter time spans I imagine.