Solaris

Excerpt from that:

Code:

/*
 * vnode ops for the /dev filesystem
 *
 * - VDIR, VCHR, CBLK, and VLNK are considered must supported files
 * - VREG and VDOOR are used for some internal implementations in
 *    the global zone, e.g. devname and devfsadm communication
 * - other file types are unusual in this namespace and
 *    not supported for now
 */

Yes. You are not supposed to create plain files under /dev. /dev is mounted using a specific file system type and is normally under the control of devfsadm.
You should only create directories and named sockets here.
One side effect of that feature is that it prevents the disk full situations that would happen should someone mistype a tape or other device while trying to archive something.