It is important to use a library or a framework because:
👍 You don't have to worry about edge cases. That means you don't need to adjust things for different browsers or containers.
👍 You don't have to update things that are not the core of your business. It helps you to focus on things that are important to your business only.
👍 You don't have to be an expert to get things done. You can leverage a framework to get some complex tasks done without knowing how to handle the operation.
So be happy to embrace their weaknesses too.