I went ahead and updated the default to 2.8.14, for now.
You make an interesting point, though. Half the time, the person requesting help doesn't bother changing any of the defaults and we find out later which version of GIMP they're using and which OS/Version they're using. I don't know if leaving it blank would help, but I suppose we could try it and see what happens.
Maybe instead of leaving it blank, it should say:
GIMP Version: (please enter GIMP version)
Either that, or leave it blank and force the user to enter a their GIMP version. Sometimes, the GIMP version is not that relevant to the question.