It wasn't much of a tradition. It just became a thing 4 years ago, and now it is furthering that precedent by saying that an opposing party no longer has to confirm a Supreme Court judge. So, basically, if a Republican President tries to appoint a nominee next year for another retired judge... and the Democrats have the Senate Majority, then they are no longer obligated to vote in that President's appointed judge until Republicans win back the Majority.
Sounds like an awful plan to me.