I've reviewed hundreds of resumes, hired great people, and hired some not great people. Sometimes they leave because of you and your company, sometimes they don't. In my experience, a history of short employment can mean one of two things:
1. This candidate is extremely talented, independent, and a self-starter. Hire these people. Now.
2. This candidate leaves before he or she is truly accountable for the code they write.
2 is very dangerous. You don't want to hire an engineer who will write a subscription billing platform and quit the week after launch. It's often tough to determine the difference between 1 and 2, and it takes many pointed questions to figure it out.