>Author here and there's nuance here but as a rule of thumb data size is a decent enough proxy.

It isn't though.

What matters is the memory footprint of the algorithm during execution.

If you're doing transformation that take constant time per item regardless of data size, sure, go for a GPU. If you're doing linear work you can't fit more than 24gb on a desktop card and prices go to the moon quickly after that.

Junior devs doing the equivalent of an outer product on data is the number one reason I've seen data pipelines explode in production.