The talk of out-of-order execution and caching doesn't make much sense. You could write in machine code and still have no idea how long a memory access will tak

The talk of out-of-order execution and caching doesn't make much sense. You could write in machine code and still have no idea how long a memory access will take or in what order your instructions will execute, so by this article's logic machine code ia a high-level language. Maybe "sequential instructions with flat memory model" is a high-level abstraction of what a modern machine does, but it is the only abstraction we have. The article proves not that C is high-level but that modern CPUs offer only a high-level interface. (And you can get around some of this, too. You can issue prefetches and so forth.)