Competition is a good thing. It encourages development and prevents complacency.
It is not a reason for fear as you describe in the post.
Indeed having no competition at all can lead to problems such as stagnation and a lack of new ideas. Why improve if you are the only game in town?
I'm not saying that would have happened to Steemit necessarily but we have all seen companies that seem to lose their minds and their way when they don't have anyone to compete against them.
Both the company and it's customers lose out in the end when that happens.
I know, plus you can't really expect that you will never have competition. Better use of time is accept it as a part of life and use it in a way that you can prosper:)
Some people want to ban it all together and that's very dangerous in my opinion, for the same reasons you just described.