MongoDB Stitch simplifies tedious coding tasks, such as interacting with third-party APIs like NumVerify, by providing an easy-to-use platform for developers. By creating a Stitch HTTP service and using a Stitch Function, the author was able to validate phone numbers from different countries in a flexible and robust manner, eliminating the need for manual regular expression code or country-specific dialling plan expertise. The use of MongoDB Stitch allows developers to focus on more complex tasks, while also ensuring that user-provided data is normalized and formatted consistently, as seen in this example where NumVerify's API was used to validate phone numbers and add international format information.