I kind of think this is also a bit misleading. Isn't the point of the phrase that you should remove the bad apple lest it affect the rest. As in, "If you leave the bad apple in the barrel it will spoil the bunch. So remove it before it does." I don't quite think that its really being misappropriated.
From your link a translated original proverb:
“Well better is a rotten apple out of the store
Than that it rot all the remnant."
So, by that logic, if you get those bad apples put before they spoil the bunch then they were "just bad apples".
To be clear I'm not saying the phrase isn't being used to minimize serious issues. But the point of the phrase wasn't that one bad apple means the entire bunch is already rotten, but that you need to remove the bad elements before the rot spreads.
I have had some time to think about it, and I should have included the word systemic instead of serious. I still stand by my overall point with regard to what the idiom actually means. I don't believe that its a good thing to misrepresent something just to prove a point.