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It makes some sense, if they're not incredibly labor intensive features. If this is something that happens to be relevant to your project, it's totally awesome... and you're really likely to stick with github as a result, unless some competitor puts a lot of work into either cloning all of github's assorted niche features, or makes some super-domain-specific project hosting site.

Plus, if it's not relevant to you, it doesn't hurt you at all.

a) They have a LOT of people on staff and the level of effort here isn't exactly rewriting the Linux kernel.

b) They're getting a lot of attention in the open data community, where the same features developers like are valued for tracking information as it's received, cleaned, and forwarded. Efforts like https://github.com/unitedstates are getting traction with some influential groups (non-profit, journalism, etc.) so I think we're going to see this as far less of a niche in the future.

In theory, it's only niche now.