Do you really think so? I've never been very good at using tap tempo buttons. This would not be accurate enough, IMO.
Honestly, most purchased music has a fairly stable tempo which is easy to beatgrid inside Rekordbox. Only every once in a while do I find a track that does not have a perfectly stable tempo, so when I find those I use Ableton Live to warp them and render to a new file which fixes the issue.