Letting your engine idle during cold start is not bad for it. It's designed to idle all day long. Idling has no load and therefore puts much less friction on key parts when the engine oil is providing sub-optimal lubrication because it's still cold. Putting load on the engine will induce more friction with cold oil than normal.
However, letting it idle will take a lot longer for the engine to achieve its optimal operating temperature. While still better to let it idle, car manufacturers and oil makers don't expect you to sit there and wait for your engine to be fully warm before you drive off. It can take it.
Just don't push the car hard until it's warmed up like everyone says. Turbos generate (and are exposed to) a lot of heat when you get on the throttle. The bearings need to be perfectly lubricated and the seals need to expand slowly as they heat up. Too rapid heating will damage the seals and stress the bearings.