WASM is not quite a stack machine

WebAssembly is fundamentally a register machine, not a true stack machine as commonly claimed, because it lacks the stack manipulation instructions (dup, swap, over) that enable efficient value reuse and common compiler optimizations. This architectural limitation means developers and compilers must introduce explicit variables to handle non-trivial computations, increasing code complexity and potentially impacting performance optimization opportunities. For IT leaders, this distinction matters because it affects how Wasm applications will compile, optimize, and perform at scale, requiring closer scrutiny of Wasm's actual capabilities versus its marketed simplicity.