> Most servers run Linux, and most software on Linux is distributed as source.
Being distributed as source code does not mean the source code is not architecture-specific. A lot of software has SIMD-optimized code paths, and it's common for these SIMD code paths to target SSE2 as the least common denominator (since AMD included SSE2 as part of the baseline of its 64-bit evolution of Intel's 32-bit architecture, every 64-bit AMD or Intel CPU on the market will have at least SSE2), so they have to be ported to NEON. And that's before considering things like JIT or FFI code.
Being distributed as source code does not mean the source code is not architecture-specific. A lot of software has SIMD-optimized code paths, and it's common for these SIMD code paths to target SSE2 as the least common denominator (since AMD included SSE2 as part of the baseline of its 64-bit evolution of Intel's 32-bit architecture, every 64-bit AMD or Intel CPU on the market will have at least SSE2), so they have to be ported to NEON. And that's before considering things like JIT or FFI code.