What? Assuming you live in the US, the government can swoop in at any time (provided they have a legal reason to do so) and demand that AWS or whoever's hosting your servers shuts them down. If you're hosting them yourself, they can raid the physical locations where you host them. If you're not in the US, I'm sure your country has equivalent security forces that would be more than capable of doing the same should the government find a reason to.
Good luck raiding every single Ethereum node in the world to take down a smart contract.
Also, you didn't address code immutability guarantees. You can change your server code at any time and your users would be none the wiser. The darknet markets, once compromised by federal agents, did exactly this, and stopped actually encrypting user messages with PGP while continuing to pretend to do so. A smart contract, unless it has upgradeability built in, offers just this sort of guarantee to its users.
Oh, and if your app deals with finance, and the US government (or your own) wants you to stop letting John Doe use your app because they just placed new sanctions on Mr. Doe? You'd better code that compliance feature up real quick or see yourself getting heavily fined or even imprisoned. Tough luck doing that sort of censorship on the blockchain -- as long as a single miner is willing to include that user's transaction, they're basically in.