If your text can be scanned easily, you stand a better chance of getting your message across. By breaking up your text into small paragraphs that flow in a logical order, your page's content will be easier on the eye and won't overwhelm your visitor. Bullets are another great feature to help you accomplish this. There is a saying that I heard applies to this topic. It's true, if every other word in a paragraph is bold then the use of the bold text loses it's effectiveness.
Web designers use bold text to draw attention to something they feel is of importance.
By using a minimal amount, your bold text will have a higher effectiveness. I know I mentioned this earlier, but thought I better reinforce it again. Then you noticed they've used bullets quite a bit. Well, the reason behind it is due to the fact that bullets break up text content quite well. Although they can be misused by placing too many bullets, this is a rare occasion.