I think you are referring to the $250k limit. It's not very practical for companies to diversify according to that limit. Apple has 50 billion in reserves, do you think they can find 200 thousand banks to spread that around?
Good question and of course, that's not likely. But then 50B in reserves isn't something you keep in a bank account, it's something you have rolled into several different financial instruments with varying levels of available liquidity.
Like… SVB