sending a whatsapp message to unsaved number

1. open Whatsapp web and login your account (it worked properly only with chrome, not with Firefox or internet explorer)
2. paste this URL in the same window. https://wa.me/491234567890 (Here 49 is country code and rest is an unsaved Whatsapp number)
3. it will show a message asking to click on a green button called 'message'. Click there
4. then it will show a message saying that it seems that you don't have the app installed. and then there will be a link called 'use Whatsapp web'. click there
5. If that unsaved number is on Whatsapp, it will reload your Whatsapp interface again with a chat window with that unsaved number after waiting for around 15-20 seconds. you can chat now. Otherwise it will say that URL is invalid.
6. It is a nice possibility to chat with unsaved numbers but I don't know why Whatsapp has made it so complex. why couldn't they simply add this feature in the main interface.