Let's be frank, b2b is boring as shit.
It's not even vaguely interesting.
The only challenge to setting up the ultimate competitor to Sage/Quickbooks is that it's so mind numbingly dull. B2B programming is an utter pile of mind-numbingly boring crap. It's not sexy because it's incredibly simple with a colossal amount of edge cases. B2B is mindbogglingly complex simple software.
B2B is just the edge cases.
It's not in the remotest bit interesting to most people. It's often bound by the most ridiculous laws and covenants.
But it'll make you a lot of money.
Do you want to read about it? No, because it's so ridiculously shallow and dull. That why no-one talks about it.
(disclosure: I am also writing b2b software)
EDIT: There was a very recent post by Intuit about the 10 million lines they've written for Quickbooks and how they manage it. That says it all to me really. 10 million lines means something has gone very, very, very wrong to me. Would you want to write a 10 million line essay about accounting? Think about your average words per line programming, that's nigh on a 50 million page essay. Just to do accounting.
Joy.