If all Plaid's customers accounts were emptied in one go, I suspect banks would reverse those transactions and tell any counterparties that lost money to pound sand.

I believe the cool kids call it a "hard fork", as in, if you are the bank that received the stolen funds and let someone withdraw them, you get forked, hard.

You wouldn’t drain all accounts all at once. Pick a couple accounts to satisfy your needs and drain them. Harder to get caught.