My perspective:

Questions why something [wasn't implemented in a standard][1] is easier to answer. As for the other question about why Microsoft didn't implement a [loopback interface][2] I don't personally feel it's a good question honestly. As for the reason questions exists on Stack Overflow, I cannot answer, since I am not involved as much in that community for a variety of reasons.

As for the reason a [Windows feature][3] doesn't do something, there isn't a way to know the specific reason. Besides, if that question were to be answered today, it would be different, considering that feature will be in [Windows 10][4]. The linked question has very little to do with PowerShell, it was erroneously, connected to PowerShell by the commenters.

There are Windows command line programs that do support that shortcut. The answer to a question should be based on fact. A question normally is in trouble if more than two people are posting an answer which presents their opinion. An answer can involve some educated guessing on what the solution might be, but if that solution isn't based on fact, then there is work to be done (to improve either on the question or the answer).

  [1]: http://superuser.com/questions/4401/whats-the-point-of-ascii-mode-in-ftp
  [2]: http://superuser.com/questions/278978/why-has-microsoft-never-implemented-a-loopback-interface-in-windows
  [3]: http://superuser.com/questions/675619/why-doesnt-windows-command-prompt-still-support-ctrl-v
  [4]: http://en.wikipedia.org/wiki/Windows_10