steemit should generate the only avatar when user lost or no-setting

 Now,lets talk abot the avatar. Steemit allows users to provide one image link to be their avatar. But this method has two problem，

• First,new user maybe dont know how to use setting function,and if they want use thier photo to be the avatar,they need upload to the internet . 
• Second,if the image upload website dont work , users will lost their avatar . 

(A is friendly than B in the home of the blog) 

 (In the comments, A is friendly than B)

 I have a idear.,maybe somebody have used Wordpress,stackoverflow,bitshares etc.Their avatarare randomly generated.

I think when new user register, it will generate one only avatar for him. Of course ,it depends on some algorithm like this(click here)；when new user dont know how to change the avatar, the system will show it.  Also be showed in the comment.  

When your image link is Invalid, the system will show the only avatar. Not show the white wrong image.

Last ,steemit maybe need Cache server!