I believe you are incorrect. A counterexample to your claim is the increasing use of FPGAs in the datacenter. And various AI engines are FPGA-based. You'll do better for a CPU in Real Silicon; but a full-featured MPU w/standard peripherals + FPGA for unusual & must-be-fast functions is hard to beat.
Tell me how much users are using FOGAs and why xillinx is just a fraction of nVidia's market cap. 5 years ago, nvidia was 2x of xillinx in market cap, now it's 10x.