I'm having a hard time seeing the pros. What can a "blockchain" do that we cannot do with existing technology? The only application so far is crypto currencies

I'm having a hard time seeing the pros. What can a "blockchain" do that we cannot do with existing technology? The only application so far is crypto currencies where it solves a very specific problem. Moreover, what even is a "blockchain"? The most basic definition would be an inversely linked list with an added hash in each node. That's not much of an innovation. On the other end of the spectrum we have something like Bitcoin with a distributed network of "miners" who compete against each other by wasting energy, because the participants do not trust one another. This is not something most people would want or need. In most use cases we probably have trusted agents, but then we don't even need a mechanism like PoW/PoS to facilitate trust. This means we're really just left with a distributed database.