Why aren't the other alt-coin developers using the same method of Stellar? (they have made 125,863 different unique accounts in few days)

They should do a pre-mine of X amount of their alt-coin (it should be public, nothing hidden), and then spread them by using Facebook accounts.

Verified Facebook accounts are good to spread alt-coins because it's difficult that there will be more than one account for person.

I know that there are exceptions, but they aren't common on a large scale.

It needs a secure (devs shouldn't have access to private keys) and easy web-wallet, and a check for a verified facebook accounts.

This will be a very easy way to spread the cryptocurrency word to common people.