Think about bitcoin that is decentralized. People running full nodes are downloading, verifying and storing hundreds of gigabytes of data because they have an incentive to do so (they want to use the decentralized currency). There are miners providing a tremendous amount of computing power to secure that network. The chain also doesn't grow that much.
Now think about a social media platform. Facebook stores about 300 petabytes of data (petabyte is 1,000,000 gigabyte). How are you going to convince regular people to run a full node that stores a fraction of that amount? It is not even possible to run such full nodes. That means centralization of full nodes to data centers!
What would be the incentive for miners (or "processors" in a different algorithm) to secure that network? Adding monetary incentive is certainly out of the question because that would mean people have to pay to post and it would also centralized mining/processors very quickly.
This is why we either see very small scale projects with tiny number of users or centralized/semi-centralized projects like steemit using the blockchain technology.
Yeah, good points.
Social media requires tons of storage. But there are other applications / services that could be built on top of decentralised infrastructures no? I'm mostly thinking about platforms such as Github, Gitlab, Bitbucket and many others. I mean, in times that we talk so much about privacy, decentralization, sovereignty, etc, it seems to e a bit contradictory that a project like Bitcoin Core is still hosted in Github and still nothing is being done to create better solutions for decentralized collaborative programming (that I know of)!