Just because they are aware of the information does not mean it was common knowledge to them prior to them using it or being told.
Forgive me for the way I am about to put this but...
How else does one get information? I can't pinpoint the exact manner in which it was gained for each specific individual but I also can't recall anyone speaking directly from personal experience and the only reason I suspect that the majority of individuals I interact with on a regular basis are aware of this is because someone ends up mentioning it virtually every time the matter of acrylic enclosures is brought up... Someone else also invariably ends up mentioning the fact that it scratches and the fact it can be drilled and cut with greater ease when building your own enclosures crops up quite often as well...
The information was obviously not ingrained at birth but... If someone is buying an enclosure made from a material they are unfamiliar with, they tend to ask, after they ask and verify the information they have been given, they know and will pass that information along. I will acknowledge that most acrylic aquariums do have the warning about cleaners somewhere in the documentation which certainly assists the spread of knowledge.
I also do not disagree that informing consumers of this situation is a bad idea, nor do I think that replacing the panels would be inappropriate, I simply feel that the attitude of the consumer, approaching the matter as if there was some unquestioning obligation for the manufacturer to do so is wrong. While I may not fully understand the intricate specifics of every single item I own, I certainly research the items to a degree that leaves me satisfied that it's what I want to buy and that it can be used in the manner I want to use it, if I make a mistake and buy the wrong item, I don't blame the manufacturer when it explodes, catches on fire, severs my limbs, permanently blinds me or leaves the air in my home tasting like tin... I accept responsibility for misuse of a product even if I was not told it couldn't be used in a certain way and I find it ridiculous that someone would try to force culpability and guilt on the manufacturer because THEY used it incorrectly. If these panels were improperly manufactured then I could see placing responsibility on the company, there has as of yet been no evidence of this... If they were used improperly, then I see placing responsibility on the buyer... there has also been no firm evidence of this, merely pattern of action, if the company were sending out badly constructed panels, there would be more than the complaint which exists (the other thread was about an improperly installed grommet of some sort).
The only other way I could see forcing the guilt onto the company and being able to demand some sort of refund would be distinct misrepresentation... If they stated they used 1/2" plexi and they send 1/8", however if they state what materials are used, or are willing to answer should the consumer be smart and ASK BEFORE SENDING THEM MONEY, then they can not be blamed, even if the materials are not suitable for the purpose the consumer wishes to utilize it for. Inflated advertisement claims are a grey area, I can keep a fifteen foot burm in a pillow case for an indefinite period of time until it really decides it wants out, so arguments about the validity of the claims on that score are sketchy, but probably the only area where clear guilt can be determined.
"A few days later, the whole side where sealed gave loose from the pressure of warping, had it not, surely more cracks would have appeared, something had to give!