I'll proffer a completely personal and unofficial comment, then, speaking as no one but myself:
I think the majority of webmasters are probably relieved and/or happy about the one-business-one-listing ideal at the ODP; if not, they probably should be. If we didn't have such a policy, then A) a webmaster would have to waste time partitioning and submitting as many pieces of his website as possible in order to keep up with the competition, even if it was less user-friendly; B) small businesses with smallish sites would be completely buried by huge businesses with huge sites; C) editors would have many times more sites to review and you'd have to wait longer than you already do; and D) you'd face the daunting prospect of one of your competitors having 25 listings out there before your 25 even come up for review--one ODP link isn't a big deal in my opinion, but if one site got 25 of them and another had 0, that would just be bound to have an effect.
It's like the way people always daydream about living in the Middle Ages. Everyone daydreams about being the princess, but 99% of the time they would really be a serf. (-: If we let everyone have multiple sites, you MIGHT be the one with a nice empire of a dozen sites while your competitors look on jealously from across the moat... but you'd more likely be one of the ones on the other side of the moat. Especially in industries like, say, bookselling, where there's a 900-pound-gorilla in the castle. All told, one listing per business is just simpler and fairer for everyone, in my opinion.