Selling is an art. Evangelizing is another. Your sales aren't necessarily evangelizers. They need help.
Egos can be your doom, just as much as your good fortune. They should thrive in what they do, with no overlap with the rest of the team, nor left-asides.
Humans have strenghts, and weaknesses. And without a team of humans, your business doesn't exist.
SaaS businesses need to get rid of old paradigms, with organizations consisting in the 4 usual departments. A 5th one needs to grow.
You think you have the best product in the world? 6 things can still make it useless and kill your business.