... and, how many programmers do you know who actually use or care about enterprise calendaring systems? Sure, there are a few, but the vast majority of programmers despise meetings, don't need to go to many of them, and don't have any real use for calendaring systems in their "real" jobs. Only managers (like me, old ex-coder for years but been in management for about a decade or so) can't live without our enterprise calendaring systems. But see, we don't count in this case.

So, if it's not of interest to programmers, it's not gonna get created in any real, stable and solid way through OSS channels...