I assume you're referring to BigCo, or even just a non-startup. If you're referring to a startup, I have to disagree with you -- revenue in the door when you're starting out, even if you have to alter your product, is invaluable. In fact, you'll likely have to alter the product from the original vision to get revenue in the door period :)
So what if you have to alter your product in 5 different, possibly incompatible, ways because 5 sales reps all sold something that you don't have? And you have to have it done by the agreed-upon delivery date (between sales and the client)? You wind up with a gigantic, unmaintainable hack.
I see your point, but if you have 5 sales reps with the authority to green-light extreme features, you're not really a startup anymore. You're officially a full-steam ahead business, or you should be.
It also comes down to the amount of money these guys are paying as well. If you're selling to say, banks, insurers, or some other larger player, you should me bringing enough revenue to justify the added expenditure. If you're selling $200+/month software tools, there had better be more customers for it somewhere. But if you're selling anything less than $100/month, you nailed it. There's a problem.
Even if it's not grand new features it hurts innovation. If you have to sideline a product that's being worked on because sales sold a feature that doesn't exist and you have to hack together a solution quickly, by definition of it being a hack it probably isn't going to scale well to other customers. And even if it does, you are not building a cohesively product at this point, you are creating a product that caters to the wishes of a specific clientele who, by the way, probably wouldn't have a problem up and leaving your business if someone else is willing to cater a little more.
