Another way to look at this is to replace "HO" with "turn onto your six" and then replay the arguments...
"Well I could have turned onto your six too, but that wouldn't have been any fun!"
"It's easy to turn onto your six, anyone can do it!"
"If everyone turns onto your six while you're turning onto their six, this game wouldn't be any fun."
Strangely enough, the core of the argument doesn't change - that the other pilot could have won too if they had used the same tactic, or that the game wouldn't be fun if everyone used the same tactic, etc. In the end, it's a lame excuse.
The truth of the matter is that the forward deflection shot (which is very rarely ever a true "head on") is a tactic like any other, just like choosing between energy fighting and turnfighting is a tactic. It has counters against it and it can be used to counter other tactics, it is simply a tool to trade a loss of angles for a guns solution.
Those who complain about front-quarter shots are those who either
a) are inexperienced at avoiding such shots,
b) would try to turn the front-quarter shot into a HO, but are poor shots themselves, or
c) don't comprehend tactics outside of cold-pass turnfights
Yet again, a look at actual WWII aerial combat and other sim communities shows the above to the norm, and paints HO complaints as what they are: excuses.