Why would I skip the anatomy scan?

At my last appointment, the midwife told me that she'd refer me to MFM for my 20 week anatomy scan because my pregnancy is higher risk. Then she immediately asked if I'd prefer to decline the referral and get a "level 1 ultrasound" with her instead. I asked why I would do that and she couldn't explain. She just told me "a lot of patients prefer" not to do the more detailed scan.

I just got a phone call from the MFM scheduler. She opened the call by saying who she was and telling me to "call back if you're even interested." I don't understand.

I'm curious to hear from anyone who has skipped the 20 week anatomy scan or knows someone who has. Why is everyone offering for me to skip the anatomy scan? Why do people skip it?

EDIT: Thank you for all the helpful replies! I didn't think of some of those reasons. I feel like I should add that the aforementioned midwife works for my obstetrician. It's common for OB practices around here to have doctor's, midwives, and nurse practitioners all seeing patients for prenatal care.