I haven't read too much into ONO, but if the platform is built on EOS, then it means it is implemented as a smart contract.
This means that anyone can write a smart contract and have it interact with the information on it.
I'm sure you've seen the bots that float around Steem quite a bit. All these bots can be implemented as smart contracts on a social network based on EOS.
For example, @coin.info, a bot that reads blog post data and post information about the coins that are mentioned in the blog.
Someone can come along and implement a smart contract that reads the all the data posted by @coin.info and make trades based on it. So on and so forth.
Why have bots that are implemented as smart-contracts? Because then you can inspect its code and make sure it does exactly what the programmer intends it to do.
You could imagine if many trading algorithms bots depend on @coin.info, they want to inspect its code to make sure it can be trusted.
Right now Steem offers only limited native smart-contracting capabilities, with escrow and beneficiaries being some of them.
I have a blog coming up that explains further in detail why a social network on the blockchain is so useful, so keep an eye out for that ;)