Blockchain AI

I'm curious.  Why has noone (yet) created an AGI (Artificial General Intelligence) that runs on the Blockchain.  Or if they have, whats its name?  

The way i see it is, it would run rampant on the decentralised blockchain, ever increasing its knowledge of everything until it finally overtakes humans, or merges us with it.

Here's what i think should be created:

An app, which interfaces with one of the many blockchains (or runs its own), which runs on computers and mobile devices.  The app functions a bit like Siri or Google Assistant and learns from people's questions by researching the information on the internet, but then if it doesn't fully understand parts of it, it asks questions from the person.  It then learns from those answers (if those answers are actual answers and not just an "i don't know").  It adds that information to its database of information, so the next time someone asks a question about it, it doesn't need to research the internet anymore, it already knows.  Or it can research the internet to compare what it knows with the information that is out there, and if the information has changed, it repeats the process of asking questions.  It uses this technique to slowly learn about everything.   The AI, running on the blockchain, also performs various problem solving functions and all the other fancy stuff an AI would do in the background.  Obviously, running on a blockchain, there would be pretty much no restrictions on its growth.  It could research and discover new technologies or information and contain a fixed directive to only ever enhance the quality of life and follow Isaac Asimov's Three Laws of Robotics.

Basically kind of like the sections under "Second Key to Creating AGI: Making It Smart" in https://waitbutwhy.com/2015/01/artificial-intelligence-revolution-1.html

Feel free to add some more ideas in the comments below on what else it could do.