Just that you need to aling on one blockchain (https://en.wikipedia.org/wiki/List_of_blockchains). So if i would be VISA or anyone else, i would just create a visachain without any need for distributed, public etc.

And cross chain transaaction is not a solved problem.

Also for financial transactions and things, i do not want them public. Now i need some magic zero knowledge system and a trust anker. Who verifies the trust anker? again a company.

Its not getting easier or frictionless at all just because blockchain and smart contracts.

I also don't see any advantage for a company to let random people run my transactions and paying others instead of just doing it myself.

Also user don't run blockchains. A normal company will just go to another company to do that the same thing as we do today. Do you think a company will just deploy a smart contract and then out of thin air someone else calls it? No another computer system would call it which also needs to run somewhere.