First of all you will need to understand what a "niche" is and why the need for it in a general sense. Now, if you understand what a niche is and why it is important in the general sense then if will help you understand if you should have in on Steemit or not.
Nobody has ever been a Jack of all trades and be a master of all or ever become a reference point when serious issues arises.
I have seen a very people on Steemit stay on their niche and this guys are slowly making names for themselves.
I love it that when I want solutions to my questions then I'm able to think of the right blog to visit and I am sure not to be dissapointed when I get there. It's not wisdom to write about everything.