Whenever I see someone say this I'm thinking the following:

If what they say is true, then x86 won because ISA doesn't matter, precisely because ISA is the public instruction set architecture. If you can convert anything to a better representation then the argument of exposing the better representation doesn't actually follow.

Additionally, you are claiming that an internal implementation detail that only Intel and AMD know about is secretly implementing your favourite instruction set, which when you think about it, is incredibly implausible and impossible to prove. It's eerily similar to an unfalsifiable theological claim.

Then there is the silly argument that x86 chips don't exist anymore, when x86 chips have distinctive differentiating factors that make them unlike chips that implement other ISAs. The most obvious one is that x86 is primarily used in the personal computing and server space. This means the chips focus on high single threaded performance with large caches and large core counts plus swappable memory and storage devices, whereas most ARM and RISC-V devices target a completely different space, primarily embedded devices where everything is included on the PCB and there are very few external interfaces. You have to be pretty delusional that an unfalsifiable claim on an internal architectural detail of a CPU core somehow invalidates the rest of the silicon that happens to be on the same die.

I hate comments like yours because they are self defeating and require a lot of effort to debunk.