Why do you think that? Named arguments aren't in conflict with any other language feature, as far as I can tell.
In some cases they do, but it is not certain. If you're using a single function with many parameters, it helps. But so does pulling up the docs for that function. You still have to decide if you want a single function with many parameters or a few small functions with fewer parameters. In fact, in many cases, what you really want is a module, not a function.
std::fs::OpenOptions is not particularly unreadable.
Capability-wise, named arguments are inferior to the builder pattern because you can't leverage the type system to enforce mutually exclusive arguments.
You also risk introducing API breakage when you change an argument's name.