Yeah, this is probably also true for TSMC, Intel and ARM. Look how slow progress is on RISC-V on the high end despite RISC-V having the best academic talent.
academic performance is a bad predictor for real world performance
Compare this to the AI ecosystem and you get a huge difference. The architecture of these AI systems is pretty well-known despite not being "open," and there is a tremendous amount of competition.
How could I verify this information?
For a concrete example, the bitmanip extensions (which provide significant increases in MIPS/MHz) were used by SiFive in commercial cores before ratification and finalization. No other company could do that because SiFive employees could just change the spec if they did. They're doing the same thing with vector/SIMD instructions now to support their machine learning ambitions.
About RISC-V: What does you think is different about RISC-V vs ARM? I can only think that ARM has been used in the wild for longer, so there is a meaningful feedback loop. Designers can incorporate this feedback into future designs. Don't give up hope on RISC-V too soon! It might have a place in IoT which needs more diverse compute.