Hear me out..
Democratic politicians should love if Bitcoin destroyed the commercial banks because it would put the money into the hands of their constituents, who by now probably outnumber republican constituents. They would no longer need to perform tricks for the banks that are contrary to the people's needs to get campaign funding to stay in power. Getting rid of the banks would be a political boon for democrats.
The continued existence of commercial banks is a political headache as it leaves politicians locked in a struggle between what the big corporate interests that fund them want and what the people want.
You can't please two masters.
But if you get rid of one…
If you transfer all that banking money back into the hands of the majority of people that already support you, you no longer need to please the big banks whose interests run contrary to your voting block.