One of the principal limitations of current Web 2.0 is that, today, most data is centralized by large entities such as Facebook, Google, Apple, etc., which control all data generated by users. The traditional business model allows these giant corporations to store and hold this data for their own purposes. If a user leaves a social network, or stops using a certain search engine, for example, he cannot get his data back. Blockchain revolutionizes this system by decentralizing data, and giving back its ownership to the person who generated it. Data can still be traded, but since everyone will truly control it as a property, people will have the liberty to choose whether they want to trade it (and get rewarded for it), or not.
Ownership of data is just the first step. The decentralized network of Web 3.0 will be completely user-centric, and, therefore, highly personalized. No intermediary is needed to, say, send an email because a third party is no longer required to provide you with all the necessary infrastructure. As a consequence, data will also be much more secure. The decentralized ledger is immutable and bulletproof, and makes data "portable" through smart contracts. Data leaks, breaches and hacks are a common occurrence in Web 2.0, but smart contracts will change this as well, stopping most forms of legal or illegal data trading and improving trust on all sides.
In other words, Web 3.0 may, once again, become that anonymous, free internet that we used to know back in its early years. Although it sounds like we're taking a step backwards, decentralization is necessary to get out from a trap where everything we do online can be tracked. The transparency of blockchain won't interfere with preserving users' privacy. Its encryption technologies are practically inviolable, and while everyone may know all the transactions occurring on the blockchain, there's no way to trace them back to a real person or a physical address. People without bank accounts will be able to receive and transfer funds, thus preserving people's anonymity to an even higher degree.