El Capitan definitely doesn't require you to create an account OR enter a credit card number, I've done it on plenty of machines. Obviously you have to create an account if you want to use iCloud, but you can simply choose not to.
I believe you, but the OS told me to upgrade to El Capitan using the App Store and the App Store told me I had to log in to iCloud and iCloud told me I had to give it a credit card. I believe you that there is a way around it, but there is also a way around getting upgraded to Windows 10. If the OS doesn't tell the average user about it, it's not part of the UX.
