Yes, we can use any interface. The issue is that I don't know whether I can trust the 3rd party products or not. For me, it's ok to use posting key, but I don't want to use the owner key for security concern. I tried to use posting key to login busy.org, but failed.
Once I reveal the fact that a reputation 69 spammer, a former steemcleaners member, adm of steemit.chat, spammed Steemit with a comment bot. The spammer, whose id is firepower, threatened me publicly on the block chain. He also banned my account at steemit.chat. We never know who is behind the 3rd party websites. That's another reason I cannot trust the 3rd party.
Yes, I am considering to build my own interface.
For all you Minnows that cant find the logo for your creating new posts and t-shirts, here it is. I created vector versions for you all. :)
Download the new Steemit Logo here and put it on T-Shirts, and share it with your friends. Thanks for supporting Steemit and for supporting your fellow Minnows!
https://steemit.com/steemit/@lifeinspired/download-steemit-s-latest-2018-logo-minnow-support-network-1