x86 has CPUID which is not all that different. The problem with feature detection is that you can't depend on programs to be well-behaved. For example in Web a

x86 has CPUID which is not all that different. The problem with feature detection is that you can't depend on programs to be well-behaved. For example in Web applications you often see accidental or deliberate assumptions "if we detect X, then Y must also be supported". Often there is a !Y path that has never been tested and therefore doesn't work.