This is a bit No True Scotsman. It's like "secured by math!" about Bitcoin - the ecosystem is rife with fraud and error.
So too with Ethereum. Given that smart contract functionality is literally Ethereum's unique selling point, you can't claim that is somehow not something that can be discussed as a problem with Ethereum. They broke the immutability guarantee for one bad smart contract, after all.
You really can't say "Ethereum is completely secure!! Except for everything that people actually use it for" without being more than a little disingenuous yourself.
Now you may legitimately argue that Ethereum is poorly designed to encourage secure contract authorship. And I would agree with you in many respects. But that is a distinct concern from the security of Ethereum itself. Conflating the two is at best confusing and at worst maliciously spurious.
WAT?