Not every component requires the same degree of decentralization. An asset settlement layer may demand high censorship resistance, whereas user interfaces, indexing, or notifications can prioritize speed and the ability to fix issues.
Good design starts with asking which trust risks the system is mitigating. If the cost of decentralization outweighs the risk eliminated, the architecture only becomes slower and harder to use. Decentralization is a tool for distributing power, not a badge to pin onto every product layer.