At least the screwshell won't rotate out of the fixture when I go to change the bulb like the lampholders do in a lot of fancy schmanzy fixtures and ceiling-fan light kits....
A few years ago every house in Vienna used to have a janitor who'd do the cleaning, change light bulbs and do minor electrical jobs. In houses without door phones he'd also lock the front door at 9pm and let visitors in.
We had a really great one. Anyway, one day he was called by the old guy who lives above us. He complained about the fuse blowing after he changed a light bulb. Wonder what, the screwshell had rotated long enough to securely twist the cloth covered wires together and strip their insulation off. As a result he had a dead short inside his porcelaine light socket.