There are almost million those do not submit their sitemap to Bing search engines that's why they loose 20% of web traffic because Google is having about 80% web traffic rest Bing and Yahoo, if you will submit sitemap of your blog to Bing it will be index by Yahoo also.
I think world's 20% is traffic is important for any blogger, the reason is quite simple it is also lot, because Bing as well
