You need to meet certain requirements such as 500 xcountry hours, 100 night etc for your ATP..The most common way to do this while getting paid is instructing. Unless you have money to burn, getting to 1500 out of pocket would be very expensive. CFIing also provides valuable learning opportunities that you prob wouldn't get doing other type of flying.

To answer your question. NO you do not "need" your CFI to get hired.