Many parents think they are, but they really aren't. That's just social pressure and group think. If parents feel like a phone isn't required, there are loads of ways to still do "all the things". My son just bought his first phone at age 16, and he's had a job since he was 14, played soccer and ultimate club teams, is very social, and president of a school club... and had scriptures at seminary.
It can all be done without a smartphone. Shoot I know young adults without smartphones navigating life just fine.
So my argument is smartphones are a choice, not a need.
But every family can make that choice if they want.