No, you can hold all the tickets for everyone on your phone if they are all on your account. I did that on our June trip so it cut down on needing everyone to have their phones. I scanned us all in the first day and then we each got the paper tickets which I also held on to. When you scan in on the first day, the cast member takes your picture and then hands you a paper ticket for entry. You can still use the digital ones on your phone if you prefer.
On the day my two kids went off on their own, I had DD14 put the app on her phone and logged into my account so they could have their tickets and
Genie+ selections. I gave them their physical tickets as well. It worked out fine. They just had to remember not to pull all 4 of us into a Genie+ selection and only the two of them.