You need a host to stay up as long as possible so people can access your website (hence, business) all the time. A 1% drop in server uptime is a lost of 87.6 hours of business opportunities. Can you afford to lose that much time in your online business? Don’t think so.
Also – you need a good web host to load your site quick. Users hate slow websites. Who has the time to wait for site loading? Not me.