I'm gonna get real cynical here. MacDonough (the parliamentarian) is a rabid Obamarxist. The parliamentarian serves at the pleasure of the Majority Leader and can be dismissed for any reason at all or none whatsoever. Why hasn't Thune fired her? Why didn't McConnell fire her?
I believe for one very simple reason. When your voters are demanding you do something you REALLY don't wanna do, a parliamentarian becomes a convenient shield to hide behind. "Sorry, Senate rules, nothing we can do..." then the standard Republicrat Three-Step* of "give us all your money and get us 60 votes and We'll GIt 'Em Next Time Fer Shur".
Then if it gets past that, it'll be used as a disposable bargaining chip where each side will agree to throw it out while blaming the other. More of the Standard Republicrat Three-Step...
*Republicrat Three-Step:
1. Drop trou.
2. P*ss in our face.
3. Tell us it's raining.