ZK is old tech but succinct, non-interactive and general purpose ZK is not. Look at SNARK and STARK, and every other research and advancement in the last 5 years. Funded by blockchain, developed for blockchain, with hash functions optimized for use in a blockchain. This modern form of ZK underpins most new blockchain bridges, light clients, and scalability solutions.
These new ZK proofs are much different than anything in the last decades, and can be used without a blockchain. But they also do fit elegantly within the context of blockchains, like having a ZKP verifier running on EVM instead of a single website like keybase.io, to further reduce points of centralization.