Blog Mickey's coverage. https://blogmickey.com/2019/09/disney-bans-outside-vendor-drop-offs-at-walt-disney-world-hotels/
I don't know about strollers, but my mother uses an ECV. We would rent it from home, and it would be waiting at the hotel when we got there. She needs it to get around the resort, not just for the parks. Now with this change instead of it waiting for us, we will have to wait around the lobby (possibly for hours) waiting for the company to bring it to us on check in day.
She can't make the walk to the room, so unless we can borrower a wheelchair, we will be sitting in that lobby until her scooter comes.
Sounds like a great start to a very expensive Disney vacation.
I get not accepting the groceries (refrigeration, fragile, etc) , but banning Strollers and ECV's seems like a bridge too far.