Yes, they taught me that in Boy Scouts too. But the burning was done as a ceremony - fold it into a triangle first, say the Pledge as it burns and then bury the ashes.
You’re talking about treating the flag with the respect due to someone who has died. That’s different.
People on the other hand, who burn flags in the open here and around the world, want America to die.
That’s the real message. The flag is far more than a physical piece of cloth. Its the flag our country was born under and for which its patriots shed their blood.