Because always is based in cases that are “easy” to debunk, cases where an apparent and “clear” misidentification is present where an object is claimed to be an anomaly.
The clear examples for these “easy picks” are the balloon shaped anomalies or anomalies that look like plastic bags or pieces of foil trapped in a thermal current.
But these are not by far the only “type” of anomalies video recorded, there are other types where that “easy” identification is not possible anymore, but these video captures are seldom choose by the people that wants to debunk the reality of these extraordinary manifestations and that is where their intellectual dishonesty gets clear.
If you really want to debunk the possible reality of these manifestations you should be able to provide a mundane “explanation” for the no so easy cases.
There are many of these no so easy cases. I want to mention that some anomalies “respond” to light signals, that is unequivocally an “anomalous” behavior.
People that had witnessed that type of response do not need this argument and we know beyond any doubts how wrong are these people that try to dismiss something that they have not even tried to observe. And some of them even claim to be “scientists”, scientists that behave exactly like the Cardinals in Galileo’s time.