Welcome to the forum.
Crowns usually eat up a lot of grafts, in a lot of cases the patient does not have enough donor to cover or recreate the crown. Clinics and patients will usually focus on the front half of a patient's scalp depending on their hair loss pattern.
If your loss is mainly the crown, then something can be done to improve it. Finasteride works very well for crown loss.
Most of my hair loss was the crown. You can read my journey here
Bigmacs hair transplant
You can see my result 12 years after my first repair surgery back in 2008.
My first hair transplants were towards the end of the 90s and 2005