Practically all banks have withdrawal limits.
Actually in many countries they are even obliged to have them, especially for online-withdrawals.
I don't know what planet you live on, but on earth bank accounts are called "demand deposits" because the client can get back ALL funds on DEMAND.
I happen to live on that same planet.
And precisely which part of "especially for online-withdrawals" did you not understand?
If I walk into my bank in Boston and present them with proper identification they MUST turn over every cent to me in my account on demand or I can sue them for mega damages under state law. That is what a demand deposit is. In fact, if a bank refuses to honor a demand deposit improperly and that causes the holder to suffer a business loss, the bank can be sued for cost + damages, typically DOUBLE what the business loss was.
If you had an account with 50 million $ in it, could you walk out of your bank with a large enough bag actually filled with those?
You would have to inform them about your withdrawal way before the actual transfer could be made.