> An adversary might still be able to take out the grid by targeting transmission infrastructure, but recovering from it should be relatively quick because the actual generators are all still intact.

You underestimate the cost and lead times of the big distribution transformers found in grid substations. As an example, a fire two years ago on a substation transformer in the state of Amapá (while another transformer was broken and awaiting maintenance, and IIRC the third transformer of the set was also damaged by the fire) led to most of that state being without power for AFAIK nearly three weeks, until a replacement sent from another substation could be installed (and as a consequence, that other substation ended up without a spare until it could receive weeks later a replacement transformer from yet another substation). Note that building a new transformer instead of shuffling them between the substations wasn't an option, because it would take too long.