I really hate whenever I try to explain how some bad rules can be abused and immediatelly get someone say shit like "If this happens in your group, change it" as if that would solve the problem. And whenever it is not soemthing you witnessed personally, then it means it never happens and could never happen.
But it is useful for someone to make rules that are balanced and lead to interesting gameplay. There are entire companies that make their business around printing rule books and selling them to people who think it's worth the money.
Think of it like this: if you have a high enough GM skill, then you'll pass whatever check God has and make the game fun. But with more balanced and interesting rules, you get a bonus. Even if it's just a +1 bonus that makes your game 5% more likely to be fun, that means everyone who plays that system gets that bonus from one person making it. You'd be crazy not to do it.
Different things work for different groups. But some things tend to work well in general, and others do not.