It’s not that people believe this - it’s just that they don’t think things through when building something. This point was mention because there are plenty of CRM/contact-management systems that only have a single phone number field per contact. Or worse: Outlook, which is expressly marketed as a contact management tool, with its arbitrary restriction of 3 phone numbers and 3 e-mail addresses per contact - or how all contacts have to have first and last names (how do I have a “company” contact? Etc). Point is, don’t be like Outlook.
