Syncing is usually not that hard. The problem is that you create tiny islands when restoring after blackout and count how much reserve you have if your largest contingency/generator trips in this case. Worst case if you pick too much load after power restoration and suddenly the largest generator trips, you are back to zero. Therefore, companies design their power restoration as small pockets, helps bring all generators online and also helps supporting different island. Synchronizing islands is a bitch but with moderns AVR and frequency regulators they are pretty doable.

Load restoration is a like a total gamble because it’s all done theoretically but rarely any engineers have seen it happen in reality.