from what I understand, the issue is moreso that it can slow down or conflict with communication on the ground. Your phone won't be able to use the cell tower for long, as it is only close enough for a short time. if I understand correctly, another concern is a phone sending messages to a cell tower out of range conflicting with transmissions related to another cell tower.

Another issue is that this could lead to reduced battery drain, as sending messages to far away cell towers takes more energy.

Some areas allow aircraft to be equipped with low power cell towers (aka picocells), which both provides cell service to the passages and prevents interference with cell towers on the ground.

note that both the US and EU are mostly hands off: airline operators may choose to allow WiFi and Bluetooth, if they can certify their craft, with the EU allowing picocells to be equipped on aircraft.

Hope you understand what I'm saying, but I can try to answer some questions.

Maybe it potentially interferes with other radio signals used for various systems during to takeoff/landing.

I thought I'd also read it was just precautionary and wasn't really necessary and that some airlines no longer require it