You want to know that if anything is wrong - you can get help or even get your money back. If it is something that could require repair, you want to know you have good service available. You want to know as much about your vendor as possible. Of course you want to know that you can trust vendors promises. On the other end of spectrum are those telling too little or nothing at all - and that hurts their business just as much.
People do that because they think they inspire trust in their visitors.
Actually they do just the opposite and hurt their business in the process. To build trust and relationships with your clients tell them the truth about yourself. It is called self-disclosure. And don't be afraid of being vulnerable - people will really respect you for admitting your flaws. The more truthful you are with your prospects and customers, the more comfortable, safe, and non-threatening they feel with you.