[70rd]

Good at what they're being programmed for is a bit of tautology.

FPGAs being selected for performance per watt was only a fairly recent phenomenon, when they were deployed on semi large scale as password crackers/cryptocurrency miners.

Their real strength is ultimately real time processing (DSP or networking), with reconfigurability often quite valuable for networking applications. For DSP applications it's usually because a MOQ of custom silicon can't be justified.