This feature is a basic requirement. Every other raw converter (aside of Luminar) has that feature.
Maybe DxO expects users to use Lightroom to organize and pre-select images to be edited.
In any case if you miss the compare and selct function you cannot fulfill the complete workflow and that’s why many users use DxO not inprofessional workflows.
I use DxO only on single files where I need the better noise correction or DxO Viewpoint plugin, I do not use Lightroom or Photoshop at all but use On1 and CaptureOne as the main tools because of the missing functions in DxO. I expected V2 to add this missing functions and make DxO a complete tool for Raw conversion.