Comment The Pi 5 line has a very narrow lane (Score 1) 70
You use a Pi 5 if you want GPIO and community support. Its appropriateness in other areas has rapidly shrunk, despite the price of the Pi being relatively stable (the 2GB model Pi 5 is like $10 more than the 2GB Pi 2).
The Pi 5 is too expensive to be used as a simple SFF PC. x86 gives you way better bang for buck but will use more power.
The Pi 5 also has a huge amount of competition as a GPIO-ready IoT dev board -- there are faster options, there are cheaper options, there are lower power options. So even in the IoT space, you're really choosing it because you want the strong community support.
The 500+ to me is perfect for a "GPIO-ready Linux dev box"