The parliamentarian ate the Republicans’ homework.
This shouldn’t be very hard. Obamacare was the most destructive and consequential bill enacted this generation. In just a few years, it has destroyed the health care industry and made insurance unaffordable. Voters elected a GOP House in 2010 and gave them a homework assignment to block Obamacare. The people did the same in 2014 when they elected a Republican Senate. Now they gave Republicans everything and expect the Obamacare fire to be extinguished altogether.
After the first budget fight of 2011, I wrote a time machine-style column at Red State predicting that even if Republicans eventually control all three branches of government, they would blame the filibuster in the Senate for not repealing Obamacare. Indeed, that nightmare has come true as GOP leaders are lying to their members and telling them that it is impossible to repeal the core of the Obamacare regulations through the filibuster-proof process of budget reconciliation.
The parliamentarian as the supreme law of the land
Why so? They are convincing members that the insuperable Senate Parliamentarian, Elizabeth MacDonough, will only permit them to repeal the taxes and the subsidies (and maybe the individual mandate) because they are budgetary in nature, but not the price-hiking insurance regulations. So in the GOP leadership’s mind, it’s case closed. There is no way to repeal the component of Obamacare that qualitatively represents 80% of the problems.
Now, before knowing any specifics about the budget process, your BS antenna should immediately set off an alarm. How could an unelected parliamentarian rule over the constitutionally-elected majority party? Obviously, you want to respect Senate tradition as much as possible and be judicious when overruling a parliamentarian. But we are not talking about some obscure area of policy here; we are talking about the future of our health care, jobs, and the ability of American families to live in dignity without unsustainable government support. How then could leadership so blithely relegate us to permanent health care insolvency, which is the only outcome of keeping the coverage regulations, simply because of an erroneous interpretation of Senate rules and precedent by the parliamentarian?
At its core, Republicans swore an oath to uphold the Constitution, not the parliamentarian’s interpretation of precedent of Senate rules. It is simply unconstitutional to force private companies to only offer actuarially insolvent plans.
Of course the insurance regulations are connected to the budget
Moreover, when you look at the specifics of budget reconciliation rules, the parliamentarian is clearly wrong and deserves to be overruled by the GOP majority, a power they can always exercise with a simple majority vote.
Obamacare is a massive entitlement that incontrovertibly qualifies for repeal through the budget reconciliation process. There is no reason why Congress can’t pass a one-sentence repeal bill and be done with it. The limitation of placing “extraneous matter” into budget-cutting bills in order to circumvent the filibuster (known as the Byrd Rule) does not apply to a law that is so complex and interconnected. This is why the four justices who ruled the individual mandate was unconstitutional would have also struck down the rest of the law. If you take away the morphine from the industry, you have to take away the pain that engenders the morphine. Just like the judiciary would have viewed the law as one entity for its purposes (had Roberts not changed his mind on individual mandate), the GOP majority has the right to view the law as such for its purposes.
Here is what the court wrote about severing the law:
When we are confronted with such a so-called “Christmas tree,” a law to which many nongermane ornaments have been attached, we think the proper rule must be that when the tree no longer exists the ornaments are superfluous. We have no reliable basis for knowing which pieces of the Act would have passed on their own. It is certain that many of them would not have, and it is not a proper function of this Court to guess which. To sever the statute in that manner "would be to make a new law, not to enforce an old one." 
Obviously, Republicans can’t stick in drilling for oil in ANWR to budget reconciliation, but the parliamentarian has no right to act like a judicial review office and strip apart each provision of an interconnected law and subject it to the Byrd Rule limitation. And if the parliamentarian issues such advice, she can be overruled with a simple majority. The parliamentarian should not be afforded more deference than the Supreme Court on statutory construction, especially when the members disagree. Also, as Heritage Action notes, the welfare reform bill used the same process to fully repeal a cash welfare program in 1996, even though not every provision had a standalone effect to reduce the deficit.
Furthermore, even if we accept the notion that some extraneous “non-budgetary” components of Obamacare, such as the death panel (IPAB) or the restriction on physician-owned hospitals, can be severed out of the process, that would not apply to the insurance regulations. Those regulations are precisely the problem that engendered the need for the funding mechanism being repealed under the current plan — the individual mandate, the taxes, and the subsidies. They served as the [inadequate] funding source to cover the unsustainable costs of the insurance regulations. That the insurance regulations were indissolubly tied to the subsidies was recognized by the Supreme Court in King v. Burwell.
Hence, it is absurd to say that the insurance regulations aren’t budgetary in nature. They are the source of the pain that engenders the need for the massive subsidies. There is no way when the Senate passed the Byrd Rule in 1985, they meant for something like this to become “extraneous matter.”
A GOP leadership that really wanted to repeal Obamacare would easily overrule the parliamentarian. In 2001, then-majority leader Trent Lott fired the parliamentarian for frustrating their budget reconciliation plans on issues much less grave than Obamacare.
In life, there are can'ts and there are won'ts. When it comes to keeping their campaign promises and delivering relief to millions of Americans who can’t find affordable health insurance, the excuse of the parliamentarian is a won't.