Where does Microsoft fit today?
Microsoft was of two minds on closed systems. Early on, it enjoyed overwhelming success versus Apple because of the tools and operating system knowledge that it shared with its developer ecosystem. It created a much broader following than Apple did in the PC era due to the richness of applications produced by that ecosystem. The Office and Windows monopolies remain intact and largely unthreatened by direct competitors to this day. Both provide a revenue stream that allows Microsoft to continue to compete on many fronts. Once launched, the ecosystem couldn't suddenly be closed down. At the same time, Microsoft couldn't bring itself to function in a more open manner, making its code open source as well as throwing the doors open to generally available, powerful tools with access to applications. It's still trying to find the proprietary space where it fits in between an Apple-like closed system and Linux/open source. Amazon, by the way, uses lots of open source code but is not itself an open system; rather it's a strongly proprietary one.