Now before I'm told how horrible a parent I am, let me explain. Like anything in life or parenting, I think it's about moderation and structure. We gave our daughter one of our older Android phones when she was about 2.5 years. We were embarking on a 5 hour flight with a toddler and a baby so yes, I was looking for distractions. I gave her a locked down phone (no dialing or data connection possible) with two educational apps and one simple drawing app. We play the apps with her and monitor her play. She can also take photos. That's it. It held her interest for a while, as did a number of other activities we brought with us on the plane, but with a limited amount of distraction available she eventually grew bored. She still has access to her phone at home now and she rarely uses it. We've taken it as a backup to many outings but find we only pull it out rarely (specifically dinner at a restaurant, close to or past bedtime, aka the witching hour).
If you give a kid a phone with the entirety of the internet and app store available with no structure, sure they'll become overwhelmed or addicted. Same thing goes for most stuff we give kids as they get older (insert car analogy). But I also think it's important to have access to the tools, connectedness, and creativity that computers and smartphones can unlock. So as my kids get older and they demonstrate they are ready, I'll unlock more functionality. But if and when I do, they can expect a lesson in how to use that new functionality safely and responsibly. If they abuse it, they lose it. I think that's about the best you can do. Maybe I'll be singing a different song in 7 years.