You've just made that up haven't you?
I have never in my life heard anyone complain about cyclists cycling on the left-hand side of the road impeding traffic wishing to turn left. I mean why would they make such a complaint? Someone cycling down the centre is impeding those driving straight on, turning right, or turning left. Cyclists who drive with due care and attention and consideration for other road users that keep into the left when they cycle aren't impeding people.
Cyclists UNDERTAKING people on the left, a completely different thing, do pose a danger to traffic wishing to turn left, and to themselves of course, but that's a different thing entirely.