It's a good thing the internet is here to pull us from the dark ages of car knowledge. More specifically, we're talking about a 3-minute YouTube video from the popular channel Engineering Explained.
For years, this guy has been explaining everything from power steering to how differentials work. However, people just wanted to know simpler stuff, like if you need to warm up the engine before driving off.
Most think you do, but with modern motors, you don't. Sensors take the temperature into consideration and create a rich fuel-to-air mix. Your only concern should be that the oil is moving, so for thicker oils, waiting a bit is recommended, but even then it's less than a minute.
Letting the engine run at idle won't do much anyway because it won't put heat into the block effectively enough, so you're just wasting fuel. But by no means does this imply that you can give it 7,000 rpm and a clutch dump. You see 'cold starts' with plenty of supercars on YouTube, but that's because they either don't belong to those people, or they are simply very rich.
Anyway, Engineering Explained says that the only counterpoint is carburated engines, which will stall when cold. This whole starting the engine and letting it run began with those, but carburetors are obsolete anyway.
You motorcycle people should also ignore this video. They break pretty easily otherwise. Two-stroke scooters are especially troublesome, as their oil is mixed in with the gas.