Yeah, as @elextr mentioned, the reason for the check is for an early failure with a message explaining the compiler isn't supported.
Another way to do it would be to do a compile-test for only `std::string_view` to also support non-C++17 compilers which might have already supported `std::string_view`, but then that would have to be updated for each new C++17 type/function we use, and especially with newer Scintilla 4/5 coming, probably LOTS of stuff.