In the beginning, there was Ethereum mainnet. It was a bit slow and quite expensive, but at least it was simple. Fast forward through the rollup-centric roadmap, and everything is fast and cheap, but with so many chains that it's just not very usable.
The ecosystem has responded, building bridges between chains, using various elegant solutions (intents to make moving assets between chains feasible and fast.
But it still doesn't feel great. Bridge apps might be getting slicker, but going to a bridge app to transfer funds is clunky and off-putting for users. And integrating bridging logic in-app is pretty onerous for app developers.
Enter resource locks, pioneered by One Balance. At first I thought these were just another gadget to speed up bridging, before understanding that they actually enable you to abstract chains and bridges altogether, spending from a user's cross-chain balance with a signature. Pretty nice!
Notably they aren't a replacement for the rest of the interop stack, they build on existing infrastructure to create a user experience which hides what happening under the hood - resource locks let developers and users think about balances, not bridges.