I don't see why. The political compass defines "libertarian" entirely in social terms, not economic. So, being strongly pro-regulation on economic/environmental issues does not reduce one's "libertarian" score. You score "libertarian" if you are against government control of personal lives, nationalism, racism, and generally are in favor of questioning authority. You are on the economic left if you simply don't think the free market will solve all problems and that corporations should get to do whatever they want.
I think Obama and many Dems are actually just barely in the left/libertarian section. The problem is that they must operate within a US political system that is controlled by corporate $ and thus skews all policy to the economic right.
As for the Political Compass giving Obama and Hillary "right/authoritarian" scores, I think that is just the nonsense political bias of those who run that site. Look at their commentary political analyses and its obvious they are left-wing extremists / socialists. They are just making up bullshit scores for mainstream Dems so they appear "authoritarian" even though any reasonable guess of what they would answer would put them on the "libertarian" half, and probably just to the left of center.
The problem is politicians get support by providing benefits to their supporters. The right get it from the rich (to cut taxes, to not control corporate misdeeds), from the military contractors and from the religious. The left get it from the unions and to some extent the social justice types--but that's more effort rather than money.
Who is going to back a left libertarian? Nobody's likely to benefit
enough to make any substantial effort worthwhile.
The Unions are dying and don't provide the Dems with near enough support to win. So, the Dems must also look to the rich and corporate America for support. This shifts the policies they push to the right of where the Dems would ideologically prefer.
In addition, Union members are not liberal or "libertarian". On most social issues they skew conservative and authoritarian. They are still mostly poorly educated whites in rural areas with healthy doses of racism, sexism, nationalism, and other "traditional values".
They have voted Dem solely for the sake of their own personal paycheck.
This has meant that as Unions die and Dems do not (or realistically cannot) save them, many lifelong Union Dems are losing their sole tie to the Dems and find the xenophobic rhetoric of Trump and the alt-right appealing.
This leaves the Dems relying on support from the educated middle class who are libertarian on social issues and have a left-leaning economic conscience, and then racial minorities and the small % of poor whites who don't fall for right-wing tribalism. These people have no organized clout and the latter groups are highly prone to not showing up to vote. So how do the Dems or any party stand a chance against the GOP who are the champions of the rich, economically powerful, and well organized religious zealots?
The reality is they don't anymore. Without support from the Union, which they lost in 2016 and maybe forever (due to Unions dying), the Dems cannot compete unless they can get the sizable non-voting left to show up and vote for them.
The problem is that many of those people are so irrationally entrenched that they won't support the Dems unless the Dems move so far to the left that they massively increase their opposition from the rich and Wall Street, which will mean a net loss in their odds of beating the GOP in the long run (even if Bernie could have pulled out a one-time victory in 2016).
Contrary to myth, the internet is not a friend of bottom-up democracy. Any hope of reducing corporate control of politics via some sort of public financing or campaign contribution restrictions has been obliterated by social media. Top-down big money will forever have disproportionate control of the discourse on social media.
The Dems only chance is to take a moderate stance on economic issues that doesn't make an enemy of every company and almost every rich person, and hope enough people with either social libertarian values and/or leftist economic goals have the sense to realize that a failure to compromise and unite means certain loss to a far worse enemy.