> They shouldn't have killed an excellent processor (the Alpha)

Parallel Alpha systems are a pain to deal with, because they lack a form of expected synchronization that every other processor has: automatic data dependency barriers. On every other platform, if you initialize or otherwise write to a value, then make a pointer point to that value, you can expect that anyone reading through that pointer gets the initialized/new value. But on Alpha, another CPU can get the new value of the pointer and then the uninitialized/old value of what it points to.

Alpha is the sole reason why the Linux kernel "smp_read_barrier_depends" barrier exists and code has to use it; on every other platform, that barrier is a no-op.