The service uptime for every single website hosting account is of crucial importance. If you are using a server which has regular problems and your website is not accessible for long periods of time, it is more likely that site visitors shall not return. Assuming you have an online store, for example, this would mean lost potential customers smaller financial gain. Your websites may even get penalized by search engines with lower rankings regardless of how good their content is. To prevent such a scenario, you should always make sure that the hosting service you get is stable. This way, the success of your site will depend only on its content and your advertising and marketing campaigns and will not be affected by hosting-related factors that you've got no control over.