[jdietrich]

High-end AV equipment like mixing consoles often use FPGAs alongside or instead of discrete DSP chips. The application demands sub-millisecond latency and deterministic performance but is too niche to justify spinning an ASIC.

IMO, those are the main factors that justify FPGA selection - low latency and hard real-time performance. I understand that military and industrial designers make extensive use of FPGAs for these reasons; the throughput isn't necessarily any better than an ordinary processor and the cost is drastically higher, but you have absolute certainty about latency.