Actually the blog side of steem does it quite well.

1. All of the data is on the blockchain.

2. Which website you choose to view that data steemit.com, busy.org, esteem, dtube.video, dlive.io doesn't matter as long as they all tap into the same blockchain.

3. Once you choose a website which will always be centralized as long as we continue to use current http and https protocols for such things. However, if your code is open source, and that source can tap into the same data then it doesn't matter that it is centralized. If someone takes out steemit, dozens of people could bring up similar sites in a matter of hours using the source code. So this mitigates the vulnerability in a centralized system.

If you don't have that then it kind of defeats the purpose of being decentralized in the first place as if it goes through a single gate keeper that can be taken down and stop it all then you might as well not decentralize at all as it is far easier to develop these things centralized and if you have centralized points of failure that cannot be gotten around to access the data then it is stupid to decentralize... doesn't really have a purpose other than marketing gimmick.