No - not a requirement - just makes it easier. You can use a card that can be scanned just as easily. Although I think for the on-ride videos like in 7DMT you need a Magic Band to have those available. So you will be missing some of the on-ride pics w/o a Magic Band I believe.
I think 7DMT is the only ride that requires a Magic Band to link your pics and video. It uses the chip to identify where you are in the ride, so you don’t even have to scan or review your picture.
Last year, my son was the only one with a Magic Band and it worked out fine. He used his for the pictures or I got a card from the photographers. But on the 7DMT, my husband and son were in one car, while my other son and I were in the car in front. Because of that, I only got a picture that focused on my husband and son. My other son and I were still in the picture, but we weren’t the focus of the picture. If that matters to you, at least get yourselves two Magic Bands.
One other thing, I noticed to link a photopass card (from the photographer) to your memory maker, you had to go into the app to add the number. Not sure if this was a temporary change or how it will be, going forward. You can have multiple photopass cards linked, but you either have to get someone to do it for you or do it through the app.