Is parsing phone numbers really a common task for startups? (I've never needed to do it). Is the use-case just validating that the user didn't accidentally type

Is parsing phone numbers really a common task for startups? (I've never needed to do it). Is the use-case just validating that the user didn't accidentally type their phone number incorrectly? (Seems if the user wants to give you the wrong phone number, they can just pick one out of a directory...)