Most of the centralized systems exist merely to establish trust between transacting individuals/entities- Amazon, Google, Uber etc. These entities are centralized and exerts so much control over the users, even to the extent that your personal data is not private (Cambridge Analytica and Facebook). They dictate terms and conditions which appear arbitrary (iOS rejecting an application) at times, tax hefty fees for using their platforms (Amazon, Uber) or exploit your data in unimaginable ways (Social credit score -China). All because there is dearth of ways in which we can establish trust between parties effectively. The reason for this behavior of centralized systems is inherent as they follow a predictive lifecycle. These entities in the beginning of their lifecycle start of by providing valuable services to the customer and as the entity grows so do their power over the customers. At the peak of growth curve what was a positive sum game turns to a zero sum game when the entities would start using data and information of the existing customers to provide complementary services to continue the growth trajectory.
The decentralized networks however works differently and does not have a centralized controller who owns the platform. The most advanced decentralized platforms are crypto platforms where behavior of any entity in the network is influenced by crypto economics which incentivizes fair play and dis-incentivizes foul play. However, designing such systems is no cakewalk and requires careful designing and implementation- any issues with design or implementation would result in catastrophic outcomes such as in the case of DAO, which eventually affects the reputation of the system and alienates the users. When implemented properly these systems offer users- control of their own data (what makes data monetization possible), liberty (no need to pay hefty taxes to middlemen for service) and a collective responsibility to sustain the system.
What comes in the way of decentralized systems are mind set (having a collaborative mindset) and current centralized entities who would resist the decentralization to retain control. Since moving from centralized systems to decentralized systems warrant some sort of collaboration between individuals in the network, some argue that people inherently are greedy and the chances of foul play are more in the absence of centralized control, the counter argument points to strong crypto economic designs which can eliminate such negative behavior, which if we look at bitcoin proves the point to a great extent. Privacy and grievance redressal are another areas of contention. Research and development in addressing the privacy aspect is underway and there are technologies like zkSNARKs already being used. However, grievance redressal in a decentralized scenario needs in-depth study and requires systems properly built on strong economic framework and up to an extend government support in terms of legal frameworks.
The deep pockets of the current centralized entities such as the Amazon, Facebook, apple etc enable them to carry out costly research and development which might let them come up with systems that are aligned to their business interests but not truly decentralized systems. The hope is upon the open source developer community, the start-ups etc who work independently from the centralized entities in developing democratized systems. The growth and development of decentralized systems thus boil down to one simple fact- who got the best developers by their side!!