Their whole "scheme", where ".." can be dealt with as a canonicalizing step BEFORE submitting the path to the OS for actual opening, seems to require refinement when symlinks are involved.
Take a perfectly spherical unix:
$ mkdir /tmp/hn
$ cd /tmp/hn
$ ln -s . foo; mkdir bar; touch baz
$ ls -l bar/../baz foo/baz foo/../baz
ls: cannot access 'foo/../baz': No such file or directory
-rw-r--r-- 1 jepler jepler 0 Nov 28 18:21 bar/../baz
-rw-r--r-- 1 jepler jepler 0 Nov 28 18:21 foo/baz
Fuscsia-with-symlinks would have some extra hoops to jump through to make rewriting act like POSIX in the case that /tmp/hn is not escaped, which surely you'd want if you went ahead and introduced symlinks.
It should be noted that this is not without precedent. Plan9 doesn't have symlinks for example, everything is done using binds. You would be surprised how many complications come up when you add symlinks to path resolution code.
Is this for technical reasons, or similar philosophical ones because symbolic links also allow for escaping from “jails”?