(having no insider info:) Because it can be used as a primary key ID across aggregated marketing databases including your voting history / party affiliation, income levels, personality and risk profiles etc etc etc. If a company wants to, and your data hygiene hasn't been tip top, your phone number is a pointer to a ton of intimate if not confidential data. Twitter was fined $150 million for asking for phone numbers under pretense of "protecting your account" or whatever but they actually used it for ad targeting.
>> Wednesday's 9th Circuit decision grew out of revelations that between 2013 and 2019, X mistakenly incorporated users' email addresses and phone numbers into an ad platform that allows companies to use their own marketing lists to target ads on the social platform.
>> In 2022, the Federal Trade Commission fined X $150 million over the privacy gaffe.
>> That same year, Washington resident Glen Morgan brought a class-action complaint against the company. He alleged that the ad-targeting glitch violated a Washington law prohibiting anyone from using “fraudulent, deceptive, or false means” to obtain telephone records of state residents.
>> X urged Dimke to dismiss Morgan's complaint for several reasons. Among other arguments, the company argued merely obtaining a user's phone number from him or her doesn't violate the state pretexting law, which refers to telephone “records.”
>> “If the legislature meant for 'telephone record' to include something as basic as the user’s own number, it surely would have said as much,” X argued in a written motion.
https://www.mediapost.com/publications/article/405501/None
>> Wednesday's 9th Circuit decision grew out of revelations that between 2013 and 2019, X mistakenly incorporated users' email addresses and phone numbers into an ad platform that allows companies to use their own marketing lists to target ads on the social platform.
>> In 2022, the Federal Trade Commission fined X $150 million over the privacy gaffe.
>> That same year, Washington resident Glen Morgan brought a class-action complaint against the company. He alleged that the ad-targeting glitch violated a Washington law prohibiting anyone from using “fraudulent, deceptive, or false means” to obtain telephone records of state residents.
>> X urged Dimke to dismiss Morgan's complaint for several reasons. Among other arguments, the company argued merely obtaining a user's phone number from him or her doesn't violate the state pretexting law, which refers to telephone “records.”
>> “If the legislature meant for 'telephone record' to include something as basic as the user’s own number, it surely would have said as much,” X argued in a written motion.
https://www.mediapost.com/publications/article/405501/None