This seems to be nothing like Diaspora. Diaspora sought to free users from a single entity owning and controlling their personal data. Altly seems to seek to simply be another single entity with control of your personal data. I don't see how that's a good thing for users.

I also doubt it'll be much of a threat to facebook...if your only argument is that Coke has a Pepsi and Chevy has a Ford, you've got a pretty weak grasp of how markets work. New colas pretty much never succeed; Pepsi and Coke were strong regional brands that went national, and there has pretty much never been a credible threat to that market from a new company. New car manufacturers are practically impossible to build in the US (Tesla is the only new car manufacturer of note in decades, and it remains to be seen how well it will fare; Saturn doesn't count, as it's just a subsidiary of GM; AMC went under after a long struggle). Markets, in general, don't care if there's competition. Markets just insure that when a dominant player shows weaknesses, someone steps into the gap. That's happened with facebook; there are many social apps that tackle small bits of the problem (like Twitter). In order to succeed, a direct competitor to facebook needs to find a chink in facebooks armor and exploit it...not just assume that everyone will flock to an "alternative to facebook" because it is an "alternative to facebook".