...and that's why water is wet!
Well copper isn't wet!
This is a great example of a red herring, or what is often called whataboutisms
It's easy to spot in this example, but is often far more subtle
It's often used to distract from the topic at hand when the person using it has a vested interest in avoiding the original topic
Particularly when dealing with the topic leads to the discomfort of cognitive dissonance, or when they are engaging disingenuously
No, it's an important topic!
You just don't want to address it
It's not necessarily that the topic isn't a valid one on it's own, it's just that it isn't relevant in this discussion
Let's use an example
If we're discussing whether there is disproportionate violence against Black folks by police, and the counter is "Well what about Black on Black violence", that's a whataboutism
But Black on Black violence is a real problem!
It's absolutely worth discussing, but the result of that discussion has no bearing on the original topic
Simply because one problem may exist, doesn't mean another problem doesn't, or isn't worth fixing until the other is fixed