Alpha was great but that wasn't enough against the convenience of just running an x86 box. It didn't find a niche quickly enough. ARM survived because they were low power. POWER survived because IBM is one big niche. MIPS died and reincarnated into RISC-V. I have no idea where Alpha would have gone had it not been dropped.
Wasn't there a problem with Alpha, that it had too weak memory model or something? Think of atomic instructions with multi CPU system. Or do I remember something wrong?