That is how I eat corn-on-the cob. Never had too many teeth, and fewer now than I did as a kid (got dentures, but they don't work on corn. At all). My dad saw me gnawing at a corn cob one day, having a tough time of it, and pulled out his stockman and sliced it out for me in a similar way to what you described.
Next day, he bought me a little jackknife, and that's been the way I've done corn ever since. Little butter, little salt, and life can't be better.
My 14yo daughter pulls out her little SAK and does it, too - braces don't work with corn cobs, either. She's done it for longer than since she got her braces, though - doesn't like getting all messy when she eats. Somebody at a church picnic asked her why she does that just as I was sitting down at the table to eat.
"That's how my dad does it."
I pulled out my knife and sliced my cob out.
"So, why do you do that?"
"Cause it's easier to eat, and you get all the corn kernels."
Simple, sensible stuff.