[xorcist]

A bit, perhaps, but not much.

At the time of bang paths, smtpd was just one of several email protocols in use. And X.400 was absolutely a competitor at the time.

A decade or two later, when it was clear that smtp had become the least common denominator between all email systems, then smtp absolutely used DNS and even had its own record type, MX.

So I don't think it is wrong to say a large part of why it won out on all other protocols was that you didn't have to mess with email routing once MX records was universally accepted.