The same as MS Windows. It is just the one people know. That does not make it a good choice for the cloud, just a familiar one.
I would absolutely prefer not to, but the work we use linux servers for doesn't require an install of scientific or similar. We deploy ubuntu based on the all seeing theory.. if we are hit by the ever feared busses, some idiot is going to have to maintain the servers. Odds are good that the linux experience on the new hires CV will be Ubuntu, so we build to that lowest common denominator. Sanity in that? Maybe.
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