Pure coincidence, I think. There certainly was no shortage of new musicals last year up against Hamilton. At that time though, Dear Evan Hansen hadn't started its Second Stage run, Come From Away hadn't started all their out of town tryouts, and Comet had to wait for the fall because of Groban's touring schedule. Just timing, really.
I am a firm believer in serendipity- all the random pieces coming together in one wonderful moment, when suddenly you see what their purpose was all along.