Just for your information: This is not feature implemented by steem(it) devs. Every form on every website which is build from textarea html tag (without style resize: none;) has this property :)

So.. in general, you learn on Steemit something what you will be able to use on all websites in the Internet, what is even better :)

Please, don't get me wrong. It is good, that you wrote this post. I am sure that a lot of people are not aware of that feature :)