This validation costs millions, which is why it is hard to enter this field, even as a fabless designer.

Many design errors are not caught even during hardware testing, but only after mass production, like the ugly MONITOR/MWAIT bug of Intel Lunar Lake.

Randomly-generated HDL code, even if it does not have syntax errors, and even if some testbench for it does not identify deviations from its specification, is not more likely to be valid when implemented in hardware, than the proverbial output of a typewriting monkey.