Why is this a requirement?
With a World Teachers TEFL certificate in your hands and part of your profile it will open doors for you. Doing a World Teachers TEFL course will help you develop skills for working and living in a foreign country. When you first travel abroad to teach, you will be in for new mind-blowing experience and maybe in for a bit of a culture shock – whether you expect in your field or not.
Having a TEFL isn't required to teach anywhere abroad, but if you want to start teaching in a country where TEFL certification is required then yes, you do need a TEFL certificate to teach abroad in that country.
Remember teaching is performance art, therefore, having an outgoing personality is an advantage. You will need to have excellent communication and listening skills. Aswell as having a passion for teaching.