The presentation you are making is both incorrect and highly misleading.
There are algorithms whose correctness depends on sequential consistency which can not be implemented in x86 without explicit barriers, for example Dekker's algorithm.
What x86 does provide is TSO semantics, not sequential consistency.
There are algorithms whose correctness depends on sequential consistency which can not be implemented in x86 without explicit barriers, for example Dekker's algorithm.
What x86 does provide is TSO semantics, not sequential consistency.