If you are referring to ACB, I can only believe it was a party line statement about forcing a SC justice through confirmation so close to a presidential election, which ran directly contrary to McConnell's previous position of refusing to have anything to do with Garland during a comparable time-frame.
If you are referring to Kavanaugh, I would think the temperament shown by him during questioning was enough to keep any Democrats from voting to confirm. Let alone their willingness to believe sexual assault claims leveled at Kavanaugh.
I'm not saying those excuses are valid enough, I'm just pointing out the likely reasons why. So, I agree with you that it was a shame.
Additionally, I think Democrats in general have been more willing over the years to confirm SC Justices than Republicans when the opposing party is the nominating party. I may be wrong in that thought because I'm not a USSC geek but, I've had the feeling for a long time that Democrats tended to play above board while Republicans were more likely to take the low road.