That's nonsense. PCI/PCIe FPGA accelerator boards have been around for ages, mostly used by the finance traders and for machine learning/math-intensive computations before cheap GPUs with much simpler programming models (no need to write e.g. matrix multiplication in VHDL/Verilog anymore) like the various programmable shaders, CUDA and OpenCL have pretty much relegated them into obscurity.

FPGA is great if you need to talk to some hardware very fast/on many pins. E.g. something like a network router where you are shuffling packets between many high speed interfaces. Or doing a lot of measurements/interfacing a bunch of high speed sensors.

But not for general purpose software - GPUs are both faster, easier to develop for (and with good tooling) and much cheaper for doing that today.