These "RADAR REQUIRED" approaches, as at DFW, have been controversial in the TERPS community as lacking a defined intermediate segment, prior to the appearance of an "IF" and RNAV. So, technically, when radar vectored, the pilot is vectored to a segment that does not exist.
Such approaches lack initial approach segments, but they are required to have an intermediate segment. The CAT III IAP referred to above has its intermediate segment from GALOP to POLKE.
Radar vectors substitute for the initial approach segment.