devenv.exe required for 64-bit builds?

I had to modify this batch file so that it doesn't search of devenv.exe when configuring for a 64-bit build, from my Parallel Studio installation:
.\compilers_and_libraries_2018\windows\bin\compilervars_arch.bat
 

Is devenv.exe really needed?  It seems to build ok without this, and configuring for a 32-bit build doesn't have this problem.  I only have the VS BuildTools installed, not the full GUI Visual Studio 2017. This is with VS Build Tools 15.6.7 + original release of Intel Parallel Studio 2018.

You can see the two lines I've rem'ed out:

::VS2017
if /i "%TARGET_VS%"=="vs2017" (
  if defined VS2017INSTALLDIR (
    rem if exist "%VS2017INSTALLDIR%\Common7\IDE\devenv.exe" (
      if exist "%VS2017INSTALLDIR%\VC\Auxiliary\Build\vcvarsall.bat" (
         set MSVS_VAR_SCRIPT="%VS2017INSTALLDIR%\VC\Auxiliary\Build\vcvarsall.bat"
         goto Calls
      )
    rem )
  )
  if /i "%TARGET_ARCH%"=="ia32" (
    if defined VS2017INSTALLDIR (
      if exist "%VS2017INSTALLDIR%\VC\Auxiliary\Build\vcvarsall.bat" (
         set TARGET_VS=vs2017
         set MSVS_VAR_SCRIPT="%VS2017INSTALLDIR%\VC\Auxiliary\Build\vcvarsall.bat"
         goto Calls
      )
    )
  )

  call :no_vs 2017 
  goto End
)