[JdeBP]

That is the current behaviour. And it's not saying what you state.

"no link" literally means no link. It's the straightforward meaning of (an ordinary, not symbolic) "link" in Unix filesystems. They cannot cross devices.

And on disc, ".." in the root is a link to the same directory. (POSIX allows for it to be this, which is the conventional Unix behaviour, or not to exist, which is the case on some non-Unix filesystems and operating systems where conceptually there is stuff "above" the root.)

Executing "cd .." ignores what is on disc at a mount point, and traverses the mount upwards.

Remember that "filesystem" has three meanings: the on-disc format of a DASD volume, the overall tree abstraction presented by the operating system, or what is presented by an FS driver.