A less malicious part of it also arises from the fact that the cheaper the modification, the worse it sounds.
You can make a car sound excellent with no drone with a $5,000 factory quality upgrade... or you can pay some bozo $100 to cut out your muffler and weld in a straight line pipe.
That may not entitle them, but it represents how people might make this choice without intentionally being a nuance in mind
I'd say a less mentioned guideline is "Please don't leave insubstantial comments playing psuedo-mod" but it's actually addressed right there in the rules you linked.
I have a 23 year old civic with little to no rust (yay California) except for a huge rust hole on the exhaust just before the muffler. So the modification is free!
I was looking into some kind of fix to wrap around the pipe but instead I had a very good deal on a 13 year old prius fall in my lap so now the civic is parked up while I decide what to do with it.
The key difference is even loud factory exhaust setups leave room for relatively quiet operation depending on how you drive.
That Elantra driver was an idiot: he went in a town and drove in sport mode and drove in a way that forces extra loud pops
If he hadn't been forcing it the car was perfectly capable of not making excessive noise.
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The $100 bozo special on the other hand has none of that: it's always loud and obnoxious.
In fact it gets more obnoxious at cruising RPM because of drone.
There are aftermarket exhausts that try to match the factory-style "not loud by default", but they're expensive because it takes careful engineering and integrating things like valves and Helmholtz resonators.
You can make a car sound excellent with no drone with a $5,000 factory quality upgrade... or you can pay some bozo $100 to cut out your muffler and weld in a straight line pipe.
That may not entitle them, but it represents how people might make this choice without intentionally being a nuance in mind