process substitution to create a virtual file doesn't work in chroot environment

[Cary Lewis]

In a cygwin process that is started either from mintty or bash directly the
following:

$ user=234

$ ./cat <(echo $user)
234
works as expected.

But after a chroot:

$ chroot . ./bash
user=234
$  ./cat <(echo $user)
./cat: /dev/fd/63: No such file or directory

In the directory I am chrooting in, I created a tmp folder, as well as
proc, proc/self, and proc/self/fd, and a dev directory.

Can someone explain why process substitution to create a virtual file
doesn't work in a chroot environment?

Thank you.