If anyone here works at Yahoo I challenge you to give me a logical reason why they require a mobile phone number in

Why Yahoo does it I don’t know but some companies like my bank use it for two factor authentication.

It's about creating a profile on you, google are the same, they demand a cell number to make a google account, right from the get go, they have your email address and cell number, you then use this account on your phone or laptop for google searches, they know what you're looking at, you use the same account to make a youtube account, so they know what you're watching. it's also the default account on android devoices.

this same cell number is used for your whatsapp account, and a whole bunch of other stuff, even your photos.... apps ask permission to access other apps.

listen to the joe rogan podcast he did with snowden, i'm not exactly a conspiracy theorist.... but then again it's hardly a secret, they tell you what they're doing....