yes, the rules have changed. You have to be there in person now to sponsor a new AP purchase, so you have to meet the person you are sponsoring at the the park and go to the AP office together, for them to be able to use your sponsorship.
You can still sponsor up to 3 new AP purchases on your AP. The other rules remain the same, you have to be an AP holder for at least one month before you can start sponsoring, and you can't use the 10% sponsorship discount if you've held an AP of any type within the 2 years prior to buying a new one. That means if someone asks you to sponsor them and they've had an AP within the last 2 years, you won't get your sponsor stamp towards your 3 sponsored APs, to allow you to extend your AP for free for 12 months.