Your cellphone number has the power to be 'the' unifying factor for different profiles that you maintain online. For example, I have multiple user ids in googl

Your cellphone number has the power to be 'the' unifying factor for different profiles that you maintain online. For example, I have multiple user ids in google for each of my businesses but I give them all my same phone number for the purpose of recovery. Now gmail does not have to do too much effort to equate the owner of all this accounts to be one person. Now assume, you give the same number to linked, facebook and google. Now you no longer need complex machine learning algorithms to match your profiles across platforms. The unified profile has all your commercial, personal and career info in one place. Ad trackers will love that! If you use the cell number in walmart etc, thats an added bonus. More importantly: Most people will have multiple email accounts but rarely more than one cell number. So it is much easier to identify the individual.