alt Hacker NewsWindows on Alpha and FX!32 were reasonably solid options, as was the general health of the Alpha ecosystem. The platform also was not overextended in dot-com boom as much as let's say Sun. Windows port was also pretty early, even if it was 32bit limited.
The big benefit for EV6 was that it had actual parts commonality with PC, and I do not mean few I/O chips like some of the others (SuperIO, network, etc.) but northbridge - anyone making a K7 motherboard could make an Alpha motherboard, and Samsung became first vendor selling both CPUs and complete systems with non-Compaq chips.
FX!32 was not good. DEC's own paper only provided results for "Byte Benchmark" (nbench) which is a few trivial compute kernels. Even that most favorable test they could find showed 500MHz 21164A performed about the same as a Pentium Pro 200, the core that would the next year be in consumer CPUs. It was also NT only, at the time not used for PCs. It's just not enough to be "as good" in a scenario like that where not only are you are massively disadvantaged by costs, but you have to break into existing markets.
EV7 and EV8 development did not go well either, costs and complexity was blowing out, EV7 slipped 18 months and planned 130nm shrink was not able to hit performance targets. EV8 was enormous and expensive totally unsuited to mass market commodity bottoms-up path of Intel, and exemplifies their retreat into high end niche rather than accept and embrace commoditization.
AMD licensed the EV6 bus, but of course there was no socket/pin compatibility between AMD and Alpha parts. So they still didn't have commodity motherboards, though that would only be one small part of the puzzle if they did have.