A modern smartphone is just a small form-factor computer that happens to have a phone app preinstalled. Some people are fine with small screens and touch "keyboards" and some people want larger sizes. The biggest difference is the OSes are very limited. It's very frustrating trying to copy and paste between apps, or "save" from one app and "load" into another. I can't have 2 or 3 apps visible on the screen at once (I'm not a "maximizer"). And data storage is confusing and inconsistent - local, cloud, filesystem, app-specific storage, etc. Can't plug in a USB thumb drive. Printing to our networked printer is not worth even trying to set up.
Real-world scenario: my wife keeps her resume (an MS Word document) on a shared drive at home. One day we were a restaurant and ran into someone with a job opening, and my wife asked me how to edit her resume on her iPhone, then attach it to an outgoing email. Hmmm... After I spent some time helping to get her file on OneDrive (using RDP and whatnot), downloading the word app, etc., my wife got so frustrated she simply gave up and said "How can people do this? I'll do it when I get home and can use the computer." Even this simple level of "content creation" on a smart phone is too complicated for the average (non techie) user. She couldn't understand why there wasn't a C: drive, or that all of the MS Word formatting wasn't available, and why she couldn't save her document to the phone for next time, etc.
I tend to used my phone as a pure consumption device. If I ever worry about customs or someone else searching my phone, I can just wipe it. Similarly, if my phone gets lost or destroyed, it doesn't really matter (except in the monetary sense). No data "lives" on my phone.