"would"
Have you? Have you ever seen it?
So, yes, it is, as far as I know, an unheard of thing. The idea that the player would hold the game hostage because the DM put his thumb on the scales of a single die roll, when the DMG gives advice that tells the DM to DO EXACTLY THIS, isn't something I've ever seen before.
Like I said, I've seen players get shirty about all sorts of things. But fudging? Seriously? I've never met anyone who cared enough to worry about it. We all knew we all did it. Heck, my group had a standard joke of, "Umm, how many HP do you have left?" and then the monster dealing one less than whatever that number was. We all knew what it meant. We also knew that sidelining one player for the next hour while we resolved the current encounter, figured out the new character, rolled up said character, figured out how to bring that character into the game and then keep playing wasn't anywhere near as much fun as just ... not doing that.
So, yeah, this is an unheard of thing.