[Atrus6]

I don't think there is anything wrong with an email provider asking me for my cell number to send me text messages, how else would they send them?

In addition, a cell phone number is NOT required to create a Google account. Sure they ask (and gender is apparently required, I just made an account), but if you leave it blank, they won't complain.

[romaniv]

There is nothing wrong with providers giving you an option to use your number for notifications. However, if we are required to provide phone number for security features that can be implemented without using phones, there are a few things wrong with it.

How can this be implemented without using a phone number? Well, the article actually contains one way - pre-shared secret codes that you print out beforehand. There are many others.