Still a cool piece of tech though.
The other use case is sorta the same thing, but is as a normal CPU with a few custom extensions. Sometimes no manufacturer's product fits your needs well and ASICs are expensive (also difficult to change), so some companies just ship customized CPUs on FPGAs with whatever extensions they need.
Xilinx's Zynq chips (FPGA with an ARM core) have been very successful, which kinda demonstrates that this is an attractive combination.
The high-end SSD market has had a lot of FPGA-based products for years, and recently many of them are using any leftover gates to add user-accessible CPUs (or occasionally ML-focused compute resources). It turns out that there are quite a few uses for having a CPU extremely close to your massive pile of data, rather than having a relatively narrow PCIe link between the storage and the CPU. These SSD controllers are usually forced to use pretty large FPGAs in order to have a high enough pin count to manage several TB of flash, and it seems that they often have logic elements to spare.