FPGAs can generally achieve much lower latencies than systems like the Pi (but so can microcontrollers). For some use cases they can be more power efficient. If

FPGAs can generally achieve much lower latencies than systems like the Pi (but so can microcontrollers). For some use cases they can be more power efficient. If you need some oddball I/O that isn't widely available in existing systems you can implement it in gateware. In general I would say there aren't a whole lot of cases where it makes sense to use an FPGA over a microcontoller or SBC given how cheap and fast they are these days. Of course like a lot of hobbyist tech stuff people will choose to use a certain technology for fun/learning. Note that the Pi didn't exist yet when this CPU was designed, the embedded world was very different 10 years ago.