There are two potential problems:
1. The difference between assembly and HDL is much greater than between bytecode and assembly, meaning it is very hard to translate one language into the other efficiently and in a short period of time
2. Hardware manufacturing speed is limited by the speed of physical processes(FPGAs can be reconfigured in tens to hundreds of milliseconds, which is good enough)
GrumpyYoungMan•1h ago
The IEEE conference on Field-Programmable Custom Computing Machines (https://www.fccm.org/) is in its 34th year, to give you an idea of how old that idea is. The answer to your question is both 1 and 2 and also 3. that FPGAs have rather poor efficiency, both in terms of cost and performance, so it's not worthwhile outside of a few niches.