It's very simple and dates back to the Airwarrior days where HO shots were really frowned upon.
The biggest complaint here is when folks use the 'it was a valid tactic in wartime" line, is that in the MA we have nothing to lose. Lives mean nothing. There is absolutely no risk to a HO shot. In that regard its seen as 'lazy', in particular by the guys who pride themselves in their ACM skills.
Having said that, I'd expect 20-30 of them to charge in here and say 'it's easy to avoid a HO". And there is some truth to that, but again, I think it comes down to a tactic that requires little effort with no risk in the MA.
The flip side to that is special events like scenarios where lives do matter. If you take a HO shot there, and the other guy blazes back, you do have something to lose. Then the 'valid tactic" argument holds some weight as you are taking a risk.
I don't blame anyone for taking that shot in a special event as it may be the only shot they get.
In the end, it's your choice. If you expect someone to salute you for a great HO shot, I think you are going to be disappointed. As will happen here, some will defend it and some will criticize it. It all comes down to how you want to play. Odds are good that if that's your only tactic, the better sticks will avoid it and kill you quick, so it's probably better to spend some time learning the bird you fly and how to bend it most effectively so when you run into those good sticks you have something to fall back on when your HO shot misses