Broken Rules?

I play in a 5e game every Saturday morning and sometimes one of the players and our DM will get to discussing obscure rules minutia. I generally don't join in on these discussions because I find them to be fairly inane. Yesterday they were talking about an "exploit"(like this is video game or something)that some youtuber had discovered in the 5e rules that allowed a wizard to summon and control an infinite number of summoned Elementals. At the time I didn't put much stock in the conversation; they were just discussing how a Dm should rule on that particular ambiguity in the rules and why it's probably overpowered, but it could be interpreted in that overpowered way, etc. 

Now, looking back at what they were talking about, I feel like they were completely missing the mark. The discussion was about what the DM ruling should be from rules perspective and that it would "break the game", etc. I think this sort of thing should be considered not from a rules or power perspective, but from a setting and world-building perspective. From my understanding this 'exploit' required the use of a 9th level spell in the first place, so the question isn't really about whether it's too powerful, but what do you envision the powerful wizards in you world being able to do? If the Gme wants the greatest wizards in the land to be capable of summoning armies of Elementals and doing other magnificent feats and probably waging destructive wars as a result, then the DM should support the 'overpowered' interpretation of the rules. On the other hand if the DM wants a more grounded setting where the high level wizards can still do amazing things, but there are limits to their capabilities, then the DM should rule in favor of disallowing the 'exploit'. 

The DM's interpretation of 'broken rules' shouldn't be about whether one or another interpretation of the rule will 'break the game', but instead about what a certain interpretation says about the DM's world and what supports their vision.

Success in D&D

"The players want to win in spite of me. The more convinced they are that their success has been stolen from within the machinations of my game, the sweeter their success will be. Therefore, I must play the villain. My machinations must be complex, demanding insight and innovation. Yes, of course, I help the players; but I do this cleverly, in ways the players do not suspect . . . covering up my intercessions with play-acting, confusion, and a little luck on the die when it happens to not go 'my way.'"(How to Run, pg 31)

Here Alexis clearly explains what I meant when I discussed the need to be a cooperative DM.

Yes, you can 'win' D&D; It's not when you reach 20th level or 36th level or attain immortality, it's when you as player achieve a goal. The players succeed when they accomplish something they set out to do, not when they complete 'the plot' a DM has devised. And this success is only meaningful if the players feel they have earned that success. Therefore, the DM must cooperate with the players to allow them to seek out their own goals within the game and also to make the accomplishment of those goals mean something. The DM has earned that success as much as the players; It's something they've accomplished together.