The combination of limitation choice and blocking policies are actually the big thing -- Netflix specifically and "ransom"/paid prioritization are recent aspects of that debate, but it really goes back to things like Comcast blocking Bittorrent, and many ISPs having rules governing what kind of applications users are permitted to use on their connection.
> Is this really a government concern that potentially some people won't be able to stream "House of Cards" without buffering?
No, the government concern is that incumbent ISPs (who often face very little local competition) will use blocking and/or paid prioritization policies to inhibit competition with their own services (many of the major incumbents also offer their own services, like streaming video services, cable TV service, phone service, etc., for which services offered over the public internet by other providers are competition.)
> Apparently there exists a technical fix by using a VPN
In the absence of the no-blocking rule, VPNs could be blocked by ISPs, thwarting this workaround.
> Why wouldn't the customers complain to/blame their ISPs just as much as Netflix?
Lack of significant competition means that you don't have to care that people are complaining to or blaming you.