Microsoft fucked up in the smartphone market so many different ways. The misunderstood the UX paradigms that would work, refused to change when Apple had obviously stolen their lunch money, stayed the bad course they were on when Android stole Apple's lunch money and then didn't even notice it has slammed Microsoft into some lockers because that's how little windows phone mattered. By the time Microsoft did like... Actual good market research and focus testing to build an actual good mobile os (maximally ironically based on their Zune UX which had failed previously because Microsoft was infinitely too slow to the mobile audio market) it was exactly as you said. The perfect mobile OS just 5 years too late to matter. More than anything what they needed to do was prove the apps you actually needed were present on their store and pay OEMs money to make windows phones to establish market share to make up for having a lower count of apps. They failed to do so. Now their actually genuinely brilliant mobile os only exists as a series of android apps that no one really gives a shit about.