Are Layers 0 really building a cross-chain future ?

I'm trying to wrap my head around what Layer 0s are actually achieving.

Cosmos has been the foundation to build a few chains through tendermint : BSC, Cronos, Osmosis or Polygon to name the most famous. Those are all EVM compatible.

Polkadot is leveraging substrate to build parachains and weave a network of specialized blockchains.

Avalanche is enabling the creation of subnets interconnected through its main chain.

But all those chain seem only to be achieving interoperability within their own ecosystems. Like intranets, local systems within the world wide web. They seem to bring more complexity rather than building simpler ways to interact with Blockchains, which is what I believe should be the goal of L0s.

Another one I've came across recently, Nervos, pretends to be able to connect them all. Its claim is that building a dApp targeting Nervos will make it compatible with all Blockchains.

That's a bold claim, but if it is true, then layer 0s will finally simplify and streamline Developer & User Experiences which may open the highway to mass adoption.

So, do you believe that Layer 0s are the real deal ? Or are they pursuing an impossible goal ? Are you aware of other L0s ?

Please share your thoughts.