Why is the Central Banks role of being the Lender of Last Resort so Crucial in an Economy?

-If a Bank borrows Short Term but Lends Long Term, they can face a Shortage of Liquidity. The Central Bank can Lend Money to ensure they don't Collapse -The Bank of England has a Predictable and Routine Scheme to Provide Liquidity. Also, there are Emergency Schemes too -The Interest Rates on Emergency Funds make an Incentive for the Bank to Behave