Myself and other contributors such as Grumpy Mike and Liudr have, for several years, been giving advice on why this reasoning is incorrect an why they always need current limiting, usually in the form of a series current limiting resistor, when driving an LED.
The length an advice has been given should be in no way shape or form supporting evidence for such advice's validity. Or we would still be living in dark ages thinking that the sun evolves around the earth.
Keep in mind that the target audience for the Arduino is not someone with an Engineering background...
Just because you think someone is "incapable" of understanding the truth doesn't justify your feeding them falsehood. You just need to figure out better ways to communicate the truth to them.
and I don't for a second buy the argument that the arduino community is 2nd rate when it comes to understanding electronics.
The bottom line is one can mess around with PWM, diodes, or some combination, but one should still use a series current limiting resistor with their LED.
The bottom line is that the laws of physics are the laws of physics, regardless of how long someone has been perpetuating anything to the contrary.