I was just talking about ownership and smart pointers.

C++'s non-owning "view" classes are a different matter, and the issue there isn't ownership but lifetime of the view vs the underlying data the view is referencing (which in case of string_view could be literally anywhere - a local array of char, a malloc'd block of memory, etc!!).

I'm not a fan of a lot of the (relatively) more recent additions to C++. I think C++14 was about the peak! Given that C++ is meant to be usable as a systems programming language, not just for applications, and given that many new features being added to C++ are really library additions, not language ones, then it's important for the language to include unsafe lower level facilities than can be used for things like that, but actually encouraging application developers to use classes like this that are error-prone by design seems questionable!