Given that you can include "hobbies" in your ECs I wouldn't feel like the contact was required.
Let's say you and your mom like skateboarding together on the weekends...would you list your mom as the contact? How ******ed is that 😀
A lot of people also lump ECs together to get around the limits on # of ECs you can list, so then you have to put contact names in the comments section for each of the ECs (ex: EC = hospital volunteer work, and in comments, volunteered in ED for 6 months, contact name, description, volunteered in NICU for 6 months, contact name, description, volunteered as patient escort for one year, etc etc).
I lumped a big pile of my college ec's into one section, because they weren't medical (student govt type stuff) and didn't see any one activity as soooo interesting it deserved its own section, but I do see the pile, overall, as relevant to my application.
If you look at your AMCAS as notes for potential interviewers, it may be easier for you to decide how to format it. How long would you like to talk about something? one minute or less, I wouldn't make it a section.😉
Warning: NO Application experience as of yet!