Accountability is half the point, actually. For example, if there's a coworker you know promises verbally then later says that never happend or they don't remember, get it in email. Likewise if you want to be sure you're on the record of "I don't agree with this idea."

Yeah I got that feeling as well, but it's not the main reason that is presented in the training.

The main issue is that your words will be taken out of context and used against the company. If you say "we are going to dominate the market" instead of "our product is going to be really well received" that can be used as evidence of anticompetitive behavior. Nevermind the fact that you're an IC and not a lawyer qualified to comment on if you are truly dominating the market.