Actually, that was not the original definition of a smartphone. Originally it only included devices that could natively run 3rd-party apps. Because BlackBerry could only run apps in a Java environment technically a BlackBerry did not qualify as a smartphone.
en.allexperts.com/e/s/sm/smartphone.htm
"A key feature of a smartphone is that additional native applications can be installed on the device."
I know it seems silly and somewhat arbitrary, but it's clear now that that highly technical definition has since given way to the broader one we all use today. Whether apps run natively in an OS or in a runtime environment isn't a meaningful distinction for most people.
Oh, and for the record plenty of people argued that the iPhone WASN'T a smartphone when it first came out. Why? Because it didn't natively run third-party apps.