There's really nothing special about Linux, but timing was right and political blunders beset all other contenders. In the end the price tag of a free UNIX was

There's really nothing special about Linux, but timing was right and political blunders beset all other contenders. In the end the price tag of a free UNIX was too good for cheap web hosts and eventually hyperscalers and Linux had insatiable hype and sidestepped most blunders. Less importantly for numbers but critically important for actual engineering talent (hyperscalers are pretty low on anything other than ops talent), high end IT applications like RDBMS and three letter acronym software from IBM, Oracle and HPC also needed to land somewhere as the commercial UNIX market shit the bed. That brought in things like RCU and high core count scalability relatively early on that turned out to be well suited for mainstream servers a short few years later. One interesting thought experiment is that cost model is the primary thing holding the WinNT kernel back as again hyperscalers tend to have very low expertise and contribution to the systems software space. A free WinNT heavily focused on the Linux (I want to say POSIX but that would be unnecessary friction at this point) personality that did containers and orchestration well would actually be interesting and a pretty easy path for MS to navigate. The space is terrible enough the MS could navigate a superior solution due to vertical integration. Think Joyent's SDC but from MS. In effect, this was what happened to Linux on the desktop -- Apple executed in a way that vertical integration can always out-engineer the bazaar model on coherence, and OS X took over desktop UNIX. Linux on the phone and embedded space I actually expect to see this erode as IoT disasters come home to roost. Things like Google's Magenta kernel, capability kernels, seL4 will probably displace it. As in the server space, the Linux personality may live on in image activation here due to entrenched developer mindset, but it's really never been a good platform to build these things on.