Yes, that's exactly what I'm saying. FPGAs simply weren't competitive for applications that were limited by sheer floating-point/integer throughput. It's not that they weren't good for a single very narrow application, they weren't good for a very broad swath of compute-intensive applications. That explains the low adoption rates.
To me, that sounds more like the problem was not a good fit for FPGA hardware.
I'm just speculating, though.