The bottleneck for building some AI datacentres and switching them on is electricity, sure, but that's not what drives growth. There also needs to be demand for the additional capacity; people need to be waiting for capacity to catch up so they can do the useful work that grows [society|GDP|something] that they aren't doing right now.

There's also very likely to be diminishing returns from additional capacity if we're near or over the limit of productive use. And there's the opportunity cost of what could have been done with that [money|land|electricity].

This is a much more complicated system than "people say they need more AI -> build datacenter -> power datacenter -> magical growth!"