In most places aluminum smelters have been located near power plants, because aluminum smelters have large electricity demand and transporting large amounts of electricity over large distances is expensive (high capacity power lines are expensive).

Electricity costs are between 40% - 50% of costs of the finished aluminum.

Also, reliability.

"Due to the nature of the process, power outages have the potential to cause damage to production cells as the molten liquids could solidify in absence of adequate current. For this reason, production facilities need to be near secure and reliable sources of energy."

https://arcticecon.wordpress.com/2012/02/15/aluminium-smelti...

"near" vs "next door or closer".

Like in all these historical cases there's been some sort of high voltage transmission in between. Sure, not a hundred mile line through god knows how many jurisdictions, but still plenty, a far cry from the "this won't pencil out if we have go farther than across the street" that we're currently seeing.

Basically what I'm saying is that if datacenters with the closest thing you'll ever see to infinite piles of cash can't expand the grid then we're in for a very rough time.