That's not a terrible explanation, if you're willing to explain why all the other dragons in Khorvaire aren't spontaneously turning nearby babies into Dragonborn, (or are they?

)
I never read "Dragons of Eberron", so I don't know how many dragons
are in Khorvaire. But I would assume that, under my theory, yes, dragonborn
would be popping up anywhere a dragon is close to.
nor why common folks who find themselves with Dragonborn babies aren't freaking out about it
I imagine some would. I also imagine that the Chamber would make efforts to keep it quiet, or to steal the babies, or to divine where the births are going to be and keep it quiet/steal the babies. Or it could be the responsibility of the Dragon causing it in the first place.
But, weird births happen in Eberron all the time. I recall that, when 4e was first announced, I asked Keith about Tieflings. His response was "My idea for tieflings was that those who are close to where planes are cotenimous would give birth to babies who embody that plane - a Tiefling born to Shavara would be warlike and aggressive, one born close to Fernia would be a pyro, etc". Half-Daelkyr (magic of eberron) are caused when people are born close an imprisoned Daelkyr. Etc etc.
I also imagine parents of half-fiends, or half-dragons, or whathaveyou, from 3e, would freak out when they were birthed due to the liasons of those species.
But I have the feeling that at the very least, a quarter of the children birthed that are Strange live to grow up.
nor how all of these Dragonborn from around the world are apparently drawn to similar beliefs.
Prophecy. It's just an inclination, not a programming.