Specifically, it's much more true in consumer than B2B. In B2B, biz dev is building partnerships, channels, distribution, obtaining resources you need at prices you can afford, all that good stuff. It's the absolute engine of your business.
If you're writing a B2C app, doesn't matter about the platform, then what biz is there to dev? In a similar sense, you need marketers, not salesmen, because your problem is getting a call-to-action out to your potential market as effectively and efficiently as possible. You can't do that door-to-door at scale.
But if you're doing enterprise software, the converse is true. You need biz dev to shape your proposition, and you need a sales force to go and hammer down doors and melt the copper in the phonelines.
Different problems, different solutions, different solvers, that's all.
I guess that's why proven coders and proven commission salespeople (and proven accountants) can always find jobs, while "big picture" folks are left unemployed, wondering why companies can't see their brilliance. Or, if they're lucky, they sue Zuckerberg because he was able to do make an actual product which never got past the great-idea-over-beer phase for them.
(Ducks...)