I can't believe mobile deep linking is such a thing that requires partnerships, integrations and announcements.

I don't see this as sufficient reason not to join a platform like Fabric. This could make it visible to a lot of developers who don't even know about deep linking, or that it can be done with an SDK. A big appeal of Fabric is also how easy it makes it to integrate kits into apps. You may be experienced enough to do the plumbing yourself, but the convenience Fabric brings lowers the bar to entry for many.

This is a great, going to give it a try. the whole attribution /analytics ecosystem is so broken

Is Fabric an alternative to React? I am unable to understand what is this app for.

No relation or similarity to React; this isn't a UI toolkit but a platform SDK.

Fabric is the rebranding of Crashlytics, a crash-reporting SDK, combined with the Twitter ecosystem SDKs, and their ad platform, and so on. It's a "Twitter Inside" SDK.

To quote an earlier comment of mine:

"a souped-up Twitter SDK + Crashlytics + their bundled ad platform MoPub. The idea is you'll develop your app with this SDK and get crash reporting, usage stats, ad serving, 'Sign in via Twitter', Twitter integration, and [a bunch of] other stuff for free."

It seems closer to pingdom-for-apps, with added Twitter.

Great move Branch