[bakje]

Running the hot water tap beforehand assumes that the dishwasher is hooked up to the hot water in the first place, which isn’t common everywhere.

Where I live this feature is called hot fill, I believe, and a lot of dishwashers don’t even support it. For those that do support its still generally not recommended to use it since the dishwasher now can’t do any rinsing with cold water, which is not only wasteful but I’ve heard the hot water can damage the water softener in your dishwasher.

But if you do hook it up to hot water (which is a lot more common in the US, I think) this makes a lot of sense.

[mitthrowaway2]

And lo, there is verily even more information presented in the video than this thread has yet revealed. For what Alec says in the video is that this purge-the-cold-water advice is specific to North America, and he even explains the reasons why!

[bakje]

Haha I have to admit I didn’t watch the whole video.

In which case my comment still stands for those who also haven’t watched the whole video, which is probably a fair amount of people

[krige]

He does mention it has to do with voltage and heating systems. I think it's something he covered on his kettle vid.

[inferiorhuman]

   the hot water can damage the water softener in your dishwasher

Most dishwashers in the US don't come with water softeners. AFAIK European made American market Bosch 500/700 series ones do, but the American made ones do not. Both would be designed for connection to a hot water supply.

As heated air drying (in the US) has fallen out of favor, hot rinse water will help things dry faster. To that end my Bosch dishwasher has an option to increase the temperature of the rinse water.