IEFBR14 is a do-nothing program -- literally all it does is issue an Assembler BR 14 command (which returns to the calling program). If you are allocating or deleting a file in JCL, you can use an IEFBR14 step to accomplish that. Since the file is not opened by IEFBR14, there are times when it makes sense to use it -- just as there are times when it makes sense to use IDCAMS. If you are deleting the VSAM file before defining it again, why not use one step of IDCAMS instead of an IEFBR14 step AND an IDCAMS step to define the VSAM file?
Bottom line: they are both effective and useful. Which to select depends upon external factors, such as whether the file is being defined again in the job.