Why do you think there is a limit on the number of times you can withdraw or transfer money in your savings account?

I think that there is a limit on the number of times  you can withdraw or transfer money in your savings account because banks only maintain a small percentage of the money people deposit on the savings accounts and most of the money is used for loans and they need to limit that to be able to have enough reserves to cover the withdrawals. If they don't put a limit people can try to withdraw all the money at the same time and the bank would not have the funds to cover that.

check the picture below.