1. Use a resistor with a LED, that is, don't depend on the internal pullup resistor.
You cannot just "depend on the internal pullup resistor" for an LED. It is not in appropriate position in the circuit.
So in my opinion, it was a very confusing, very unnecessary smartass remark to bring that hack into the game here.
Now then, if the built-in resistor on the Arduino board diminishes the current, why not build a breadboard layout with a LED and no external resistor, for use with the DigitalInputPullup Example?
I answered the question. Answering to OP is "unnecessary smartass remark"?
Now then, if the built-in resistor on the Arduino board diminishes the current