Probably more people than you think know about Alpas, but very few people have owned/do own one of their cameras.
They've made high-end, very expensive, well-regarded 35mm and (more recently)
MF and LF camera bodies for a long time, but they're like high-end Hi-Fi manufacturers, in that the people with enough money to buy them appreciate them, but their advantages have many other people scratching their heads.
Then again, if they had a real choice, who'd have a Bugatti Veyron, rather than a BMW M3 or a Porsche, and why? There's no one answer to that, just as there isn't for who'd buy a Leica or an Alpa instead of a Nikon (let's keep it neutral here). And, just to keep things on topic, you'll probably find someone else's bits in any of those cars, so why not Alpa's cameras, too?