[koyao]

And LinkedIn is now asking me to enter my phone number:

"Add an extra layer of security to your account. Add your phone number."

Leaking my email / password is bad enough; I'm not going to give them my phone number for more damages!

[eru]

Also, access to your phone (or rather anything send to your phone number) is trivial to get via social engineering the telco.

(The attack is not very scalable, but easy enough to pull off against individual targets.)