Pretend that there were nobody there besides the pro with a camera. He could work unencumbered, with nobody stepping into his shots. No idiot firing off a flash while he is shooting available light. Because as soon as one person gets up and tries to take pictures, it emboldens others to do the same. Added people taking pictures are a distraction because the subject can tend to look around instead of looking where the pro is. Flash pictures can make people blink. Others people taking pictures get in the way and they also suck out time the pro could be using.
The pro can't really say anything to people with cameras because he doesn't want to poison the atmosphere, upset the wedding couple, parents etc.
He loses money from sales to family of extra prints. A known fact. Check with PPA.
So while you pretend you are there because the bride or groom asked you to, you are indeed disrupting the pro whether you choose to believe it or not.
And your example of hacks is not the same. Your example is about competition. Mine is about people on the scene while I'm engaging the subject. Completely different. Everybody has competition, no matter how professional they are. Your analogy would only work if someone was installing air conditioning at the same time, same place while you were and disrupting your work.