I (and others) have often connected 12 and 24 volts signals to inputs of 5 volt devices, using a 220k resistor.
No one is disputing your statement that by adding an external series resistor one can apply higher then Vcc to a Arduino I/O pin, heck I've seen in the past a PIC application note where they wired 120vac to a input pin (with a rather large series resistor!) to utilize the 60hz for a timing reference.
What we are saying to the OP was that wiring a higher then Vcc voltage directly to a I/O pin (without any external current limiting resistance) will take out the I/O pin, plain and simple.
What was it you though we didn't understand again?
Lefty