Blueprint interface still need cast to! whats the point of using BPI?

I have been learning to use BPI and a lot of people are saying they are better than casting for large amounts and better performance. okay fine. So every tutorial I looked into does not eliminate the use of casting. Regardless of using BPI I still have to cast to get a reference form another blueprint.

For example: here I have to cast to my character to get its child location. lol whats the point of using BPi I could just simply cast it then.

Please tell me what I am doing wrong

Make the connection directly

You might have to use ‘get player character’.