Local models are not the same as the giant ones in data centers. They're in about the about the same ballpark as running a AAA game on max settings.
Sure, it's more computationally-expensive than running an HTML selection, but it's also not "staggering" by any reasonable stretch.
I think “staggering” is a pretty accurate way of putting it if blocking ads is in the same ballpark as running a AAA game on max settings.