Some people complain that Doctor Strange is too similar to Iron Man, both the characters and the stories in their movies. While that may be true, that's only because they are both very well told stories... they are just told very similarly. Doctor Strange is just as cocky as Tony Stark, but at the end of the day, they are very different characters (as is evident by their interactions in 'Infinity War').
Doctor Strange gives us a really good sense that there are bigger powers at work in the universe than anything that the Avengers have ever faced. The only reason Dormammu could be defeated is through an infinity stone. Ultron? He's nothing compared to other-dimensional beings like Thanos. Luckily he has that time stone to reverse time if anything ever goes wrong. He still has that thing, right?